diff --git a/boards/acd52832/include/periph_conf.h b/boards/acd52832/include/periph_conf.h
index 06cac33fbd..fcecf37af9 100644
--- a/boards/acd52832/include/periph_conf.h
+++ b/boards/acd52832/include/periph_conf.h
@@ -61,7 +61,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -77,7 +77,7 @@ static const i2c_conf_t i2c_config[] = {
     }
 };
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/airfy-beacon/include/periph_conf.h b/boards/airfy-beacon/include/periph_conf.h
index 664dc57fe6..f10fc2d679 100644
--- a/boards/airfy-beacon/include/periph_conf.h
+++ b/boards/airfy-beacon/include/periph_conf.h
@@ -53,7 +53,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -77,7 +77,7 @@ static const i2c_conf_t i2c_config[] = {
     }
 };
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
diff --git a/boards/arduino-zero/include/periph_conf.h b/boards/arduino-zero/include/periph_conf.h
index 09eed72b8c..b458f5fbbf 100644
--- a/boards/arduino-zero/include/periph_conf.h
+++ b/boards/arduino-zero/include/periph_conf.h
@@ -120,7 +120,7 @@ static const tc32_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tc3
 #define TIMER_1_ISR         isr_tc4
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -154,7 +154,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          isr_sercom5
 #define UART_1_ISR          isr_sercom0
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -215,7 +215,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -235,7 +235,7 @@ static const i2c_conf_t i2c_config[] = {
     }
 };
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
diff --git a/boards/b-l072z-lrwan1/include/periph_conf.h b/boards/b-l072z-lrwan1/include/periph_conf.h
index 2b3b6292d9..7329dad3f8 100644
--- a/boards/b-l072z-lrwan1/include/periph_conf.h
+++ b/boards/b-l072z-lrwan1/include/periph_conf.h
@@ -47,7 +47,7 @@ static const dma_conf_t dma_config[] = {
 #define DMA_SHARED_ISR_1            isr_dma1_channel4_5_6_7
 #define DMA_SHARED_ISR_1_STREAMS    { 2, 3, 4 } /* Indexes 2, 3 and 4 of dma_config share the same isr */
 
-#define DMA_NUMOF           (sizeof(dma_config) / sizeof(dma_config[0]))
+#define DMA_NUMOF           ARRAY_SIZE(dma_config)
 #endif
 /** @} */
 
@@ -93,7 +93,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_usart2)
 #define UART_1_ISR          (isr_usart1)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -155,7 +155,7 @@ static const spi_conf_t spi_config[] = {
     },
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/b-l475e-iot01a/include/periph_conf.h b/boards/b-l475e-iot01a/include/periph_conf.h
index 4bfbb9d87c..674c5cfeec 100644
--- a/boards/b-l475e-iot01a/include/periph_conf.h
+++ b/boards/b-l475e-iot01a/include/periph_conf.h
@@ -87,7 +87,7 @@ static const dma_conf_t dma_config[] = {
 #define DMA_2_ISR  isr_dma1_channel4
 #define DMA_3_ISR  isr_dma2_channel3
 
-#define DMA_NUMOF           (sizeof(dma_config) / sizeof(dma_config[0]))
+#define DMA_NUMOF           ARRAY_SIZE(dma_config)
 #endif
 /** @} */
 
@@ -107,7 +107,7 @@ static const timer_conf_t timer_config[] = {
 
 #define TIMER_0_ISR         isr_tim5
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -152,7 +152,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_usart1)
 #define UART_1_ISR          (isr_uart4)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -172,7 +172,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -218,7 +218,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -253,7 +253,7 @@ static const i2c_conf_t i2c_config[] = {
 #define I2C_0_ISR           isr_i2c1_er
 #define I2C_1_ISR           isr_i2c2_er
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/calliope-mini/include/periph_conf.h b/boards/calliope-mini/include/periph_conf.h
index 3e59b6d331..5b4f1e59c9 100644
--- a/boards/calliope-mini/include/periph_conf.h
+++ b/boards/calliope-mini/include/periph_conf.h
@@ -54,7 +54,7 @@ static const i2c_conf_t i2c_config[] = {
     }
 };
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
diff --git a/boards/cc2538dk/include/periph_conf.h b/boards/cc2538dk/include/periph_conf.h
index 75597e4d7e..a116bbfa42 100644
--- a/boards/cc2538dk/include/periph_conf.h
+++ b/boards/cc2538dk/include/periph_conf.h
@@ -53,7 +53,7 @@ static const timer_conf_t timer_config[] = {
     },
 };
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 
 #define TIMER_IRQ_PRIO      1
 /** @} */
@@ -76,7 +76,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          isr_uart0
 
 /* macros common across all UARTs */
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 
 /** @} */
 
@@ -94,7 +94,7 @@ static const i2c_conf_t i2c_config[] = {
     },
 };
 
-#define I2C_NUMOF               (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF               ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
@@ -111,7 +111,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -124,7 +124,7 @@ static const adc_conf_t adc_config[] = {
     GPIO_PIN(0, 6), /**< GPIO_PA6 = ADC_ALS_PIN */
 };
 
-#define ADC_NUMOF           (sizeof(adc_config) / sizeof(adc_config[0]))
+#define ADC_NUMOF           ARRAY_SIZE(adc_config)
 /** @} */
 
 /**
diff --git a/boards/cc2650-launchpad/include/periph_conf.h b/boards/cc2650-launchpad/include/periph_conf.h
index 5c6ca89a1a..f1c42eca7f 100644
--- a/boards/cc2650-launchpad/include/periph_conf.h
+++ b/boards/cc2650-launchpad/include/periph_conf.h
@@ -62,7 +62,7 @@ static const timer_conf_t timer_config[] = {
  }
 };
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
diff --git a/boards/cc2650stk/include/periph_conf.h b/boards/cc2650stk/include/periph_conf.h
index 22d95582e0..9e8a0ef9da 100644
--- a/boards/cc2650stk/include/periph_conf.h
+++ b/boards/cc2650stk/include/periph_conf.h
@@ -60,7 +60,7 @@ static const timer_conf_t timer_config[] = {
     }
 };
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
diff --git a/boards/common/arduino-due/include/periph_conf.h b/boards/common/arduino-due/include/periph_conf.h
index 2c94b12a31..bcd6e5bba2 100644
--- a/boards/common/arduino-due/include/periph_conf.h
+++ b/boards/common/arduino-due/include/periph_conf.h
@@ -59,7 +59,7 @@ static const timer_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tc0
 #define TIMER_1_ISR         isr_tc3
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -107,7 +107,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_2_ISR          isr_usart1
 #define UART_3_ISR          isr_usart3
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -125,7 +125,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -140,7 +140,7 @@ static const pwm_chan_conf_t pwm_chan[] = {
 };
 
 #define PWM_NUMOF           (1U)
-#define PWM_CHAN_NUMOF      (sizeof(pwm_chan) / sizeof(pwm_chan[0]))
+#define PWM_CHAN_NUMOF      ARRAY_SIZE(pwm_chan)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/common/arduino-mkr/include/periph_conf.h b/boards/common/arduino-mkr/include/periph_conf.h
index d8ad13711d..8ce427b6c2 100644
--- a/boards/common/arduino-mkr/include/periph_conf.h
+++ b/boards/common/arduino-mkr/include/periph_conf.h
@@ -118,7 +118,7 @@ static const tc32_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tc3
 #define TIMER_1_ISR         isr_tc4
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -141,7 +141,7 @@ static const uart_conf_t uart_config[] = {
 /* interrupt function name mapping */
 #define UART_0_ISR          isr_sercom5
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -165,7 +165,7 @@ static const pwm_conf_t pwm_config[] = {
 };
 
 /* number of devices that are actually defined */
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -230,7 +230,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -248,7 +248,7 @@ static const i2c_conf_t i2c_config[] = {
         .flags    = I2C_FLAG_NONE
      }
 };
-#define I2C_NUMOF          (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF          ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
diff --git a/boards/common/atmega/include/periph_conf_atmega_common.h b/boards/common/atmega/include/periph_conf_atmega_common.h
index a08087990b..de95f5a303 100644
--- a/boards/common/atmega/include/periph_conf_atmega_common.h
+++ b/boards/common/atmega/include/periph_conf_atmega_common.h
@@ -349,7 +349,7 @@ extern "C" {
 #endif
     };
 
-    #define PWM_NUMOF           (sizeof(pwm_conf) / sizeof(pwm_conf[0]))
+    #define PWM_NUMOF           ARRAY_SIZE(pwm_conf)
 #endif
 #endif /* PWM_NUMOF */
 /** @} */
diff --git a/boards/common/esp32/include/periph_conf_common.h b/boards/common/esp32/include/periph_conf_common.h
index 6d1bdc8ab0..9cef5906ca 100644
--- a/boards/common/esp32/include/periph_conf_common.h
+++ b/boards/common/esp32/include/periph_conf_common.h
@@ -25,6 +25,7 @@
 
 /* include periph_cpu.h to make it visible in any case */
 #include "periph_cpu.h"
+#include "kernel_defines.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -59,7 +60,7 @@ static const gpio_t adc_channels[] = ADC_GPIOS;
  *
  * @note ADC_NUMOF definition must not be changed.
  */
-#define ADC_NUMOF   (sizeof(adc_channels) / sizeof(adc_channels[0]))
+#define ADC_NUMOF   ARRAY_SIZE(adc_channels)
 /** @} */
 
 /**
@@ -91,7 +92,7 @@ static const gpio_t dac_channels[] = DAC_GPIOS;
  *
  * @note DAC_NUMOF definition must not be changed.
  */
-#define DAC_NUMOF   (sizeof(dac_channels) / sizeof(dac_channels[0]))
+#define DAC_NUMOF   ARRAY_SIZE(dac_channels)
 /** @} */
 
 /**
@@ -127,7 +128,7 @@ static const i2c_conf_t i2c_config[] = {
  *
  * @note I2C_NUMOF definition must not be changed.
  */
-#define I2C_NUMOF   (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF   ARRAY_SIZE(i2c_config)
 
 /** @} */
 
@@ -203,7 +204,7 @@ static const spi_conf_t spi_config[] = {
  *
  * @note SPI_NUMOF definition must not be changed.
  */
-#define SPI_NUMOF   (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF   ARRAY_SIZE(spi_config)
 
 /** @} */
 
diff --git a/boards/common/iotlab/include/periph_conf_common.h b/boards/common/iotlab/include/periph_conf_common.h
index 4daebc8f56..937f6ce917 100644
--- a/boards/common/iotlab/include/periph_conf_common.h
+++ b/boards/common/iotlab/include/periph_conf_common.h
@@ -81,7 +81,7 @@ static const dma_conf_t dma_config[] = {
 #define DMA_0_ISR  isr_dma1_channel4
 #define DMA_1_ISR  isr_dma1_channel6
 
-#define DMA_NUMOF           (sizeof(dma_config) / sizeof(dma_config[0]))
+#define DMA_NUMOF           ARRAY_SIZE(dma_config)
 #endif
 /** @} */
 
@@ -109,7 +109,7 @@ static const timer_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tim2
 #define TIMER_1_ISR         isr_tim3
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -146,7 +146,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_usart1)
 #define UART_1_ISR          (isr_usart2)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -183,7 +183,7 @@ static const i2c_conf_t i2c_config[] = {
 
 #define I2C_0_ISR           isr_i2c1_ev
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
diff --git a/boards/common/kw41z/include/cfg_i2c_default.h b/boards/common/kw41z/include/cfg_i2c_default.h
index cd04ab0ebd..41f9b2eee8 100644
--- a/boards/common/kw41z/include/cfg_i2c_default.h
+++ b/boards/common/kw41z/include/cfg_i2c_default.h
@@ -43,7 +43,7 @@ static const i2c_conf_t i2c_config[] = {
         .sda_pcr = (PORT_PCR_MUX(3)),
     },
 };
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 #define I2C_0_ISR           (isr_i2c1)
 /** @} */
 
diff --git a/boards/common/kw41z/include/periph_conf_common.h b/boards/common/kw41z/include/periph_conf_common.h
index 82de9a3c2f..6eafe08695 100644
--- a/boards/common/kw41z/include/periph_conf_common.h
+++ b/boards/common/kw41z/include/periph_conf_common.h
@@ -116,7 +116,7 @@ static const uart_conf_t uart_config[] = {
         .type   = KINETIS_LPUART,
     },
 };
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 #define LPUART_0_ISR        isr_lpuart0
 /* Use MCGIRCLK (internal reference 4 MHz clock) */
 #define LPUART_0_SRC        3
diff --git a/boards/common/nrf51/include/cfg_timer_01.h b/boards/common/nrf51/include/cfg_timer_01.h
index 0377f41061..956e982dec 100644
--- a/boards/common/nrf51/include/cfg_timer_01.h
+++ b/boards/common/nrf51/include/cfg_timer_01.h
@@ -49,7 +49,7 @@ static const timer_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_timer0
 #define TIMER_1_ISR         isr_timer1
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/common/nrf51/include/cfg_timer_012.h b/boards/common/nrf51/include/cfg_timer_012.h
index cf10da7ac1..15f69fe959 100644
--- a/boards/common/nrf51/include/cfg_timer_012.h
+++ b/boards/common/nrf51/include/cfg_timer_012.h
@@ -56,7 +56,7 @@ static const timer_conf_t timer_config[] = {
 #define TIMER_1_ISR         isr_timer1
 #define TIMER_2_ISR         isr_timer2
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/common/nrf52/include/cfg_spi_default.h b/boards/common/nrf52/include/cfg_spi_default.h
index 2847a962f3..cfd029ca82 100644
--- a/boards/common/nrf52/include/cfg_spi_default.h
+++ b/boards/common/nrf52/include/cfg_spi_default.h
@@ -39,7 +39,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/common/nrf52/include/cfg_timer_default.h b/boards/common/nrf52/include/cfg_timer_default.h
index 8dd673806f..a7d6786577 100644
--- a/boards/common/nrf52/include/cfg_timer_default.h
+++ b/boards/common/nrf52/include/cfg_timer_default.h
@@ -48,7 +48,7 @@ static const timer_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_timer1
 #define TIMER_1_ISR         isr_timer2
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/common/nrf52xxxdk/include/periph_conf_common.h b/boards/common/nrf52xxxdk/include/periph_conf_common.h
index 3b8f2cec21..e82172bf28 100644
--- a/boards/common/nrf52xxxdk/include/periph_conf_common.h
+++ b/boards/common/nrf52xxxdk/include/periph_conf_common.h
@@ -38,7 +38,7 @@ extern "C" {
 static const pwm_conf_t pwm_config[] = {
     { NRF_PWM0, { 28, 29, 30, 31 } }
 };
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/common/nucleo64/include/board.h b/boards/common/nucleo64/include/board.h
index c2787697fa..83ab8d62fa 100644
--- a/boards/common/nucleo64/include/board.h
+++ b/boards/common/nucleo64/include/board.h
@@ -89,7 +89,7 @@ static const motor_driver_config_t motor_driver_config[] = {
     },
 };
 
-#define MOTOR_DRIVER_NUMOF           (sizeof(motor_driver_config) / sizeof(motor_driver_config[0]))
+#define MOTOR_DRIVER_NUMOF           ARRAY_SIZE(motor_driver_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/common/particle-mesh/include/periph_conf_common.h b/boards/common/particle-mesh/include/periph_conf_common.h
index 829bf70b15..195750eb19 100644
--- a/boards/common/particle-mesh/include/periph_conf_common.h
+++ b/boards/common/particle-mesh/include/periph_conf_common.h
@@ -43,7 +43,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/common/remote/include/periph_common.h b/boards/common/remote/include/periph_common.h
index 8565567285..19db083fb9 100644
--- a/boards/common/remote/include/periph_common.h
+++ b/boards/common/remote/include/periph_common.h
@@ -61,7 +61,7 @@ static const timer_conf_t timer_config[] = {
     },
 };
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 
 #define TIMER_IRQ_PRIO      1
 /** @} */
@@ -100,7 +100,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          isr_uart1
 
 /* macros common across all UARTs */
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 
 /** @} */
 
diff --git a/boards/common/saml1x/include/periph_conf.h b/boards/common/saml1x/include/periph_conf.h
index 56fbe2e3eb..6650b10650 100644
--- a/boards/common/saml1x/include/periph_conf.h
+++ b/boards/common/saml1x/include/periph_conf.h
@@ -51,7 +51,7 @@ static const tc32_conf_t timer_config[] = {
 /* Timer 0 configuration */
 #define TIMER_0_CHANNELS    2
 #define TIMER_0_ISR         isr_tc0
-#define TIMER_NUMOF         (sizeof(timer_config)/sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -74,7 +74,7 @@ static const uart_conf_t uart_config[] = {
 /* interrupt function name mapping */
 #define UART_0_ISR          isr_sercom2_2
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -96,7 +96,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -115,7 +115,7 @@ static const i2c_conf_t i2c_config[] = {
     }
 };
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
diff --git a/boards/common/stm32/include/cfg_i2c1_pb8_pb9.h b/boards/common/stm32/include/cfg_i2c1_pb8_pb9.h
index d1e734f5ee..f37a5b2290 100644
--- a/boards/common/stm32/include/cfg_i2c1_pb8_pb9.h
+++ b/boards/common/stm32/include/cfg_i2c1_pb8_pb9.h
@@ -71,7 +71,7 @@ static const i2c_conf_t i2c_config[] = {
 #define I2C_0_ISR           isr_i2c1
 #endif
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/common/stm32/include/cfg_timer_tim2.h b/boards/common/stm32/include/cfg_timer_tim2.h
index 9590ae32c9..e7cbc69b85 100644
--- a/boards/common/stm32/include/cfg_timer_tim2.h
+++ b/boards/common/stm32/include/cfg_timer_tim2.h
@@ -49,7 +49,7 @@ static const timer_conf_t timer_config[] = {
 
 #define TIMER_0_ISR         isr_tim2
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/common/stm32/include/cfg_timer_tim5.h b/boards/common/stm32/include/cfg_timer_tim5.h
index 021ba6e528..bc6e388655 100644
--- a/boards/common/stm32/include/cfg_timer_tim5.h
+++ b/boards/common/stm32/include/cfg_timer_tim5.h
@@ -41,7 +41,7 @@ static const timer_conf_t timer_config[] = {
 
 #define TIMER_0_ISR         isr_tim5
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/common/stm32f103c8/include/periph_conf.h b/boards/common/stm32f103c8/include/periph_conf.h
index 297948a65b..862402526a 100644
--- a/boards/common/stm32f103c8/include/periph_conf.h
+++ b/boards/common/stm32f103c8/include/periph_conf.h
@@ -113,7 +113,7 @@ static const timer_conf_t timer_config[] = {
 #define TIMER_1_ISR         isr_tim3
 #define TIMER_2_ISR         isr_tim4
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -151,7 +151,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          (isr_usart2)
 #define UART_2_ISR          (isr_usart3)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -185,7 +185,7 @@ static const i2c_conf_t i2c_config[] = {
 #define I2C_0_ISR           isr_i2c1_ev
 #define I2C_1_ISR           isr_i2c2_ev
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
@@ -205,7 +205,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -253,7 +253,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/ek-lm4f120xl/include/periph_conf.h b/boards/ek-lm4f120xl/include/periph_conf.h
index 818c8e097a..3875676735 100644
--- a/boards/ek-lm4f120xl/include/periph_conf.h
+++ b/boards/ek-lm4f120xl/include/periph_conf.h
@@ -160,7 +160,7 @@ static const spi_conf_t spi_confs[] = {
     },
 };
 
-#define SPI_NUMOF (sizeof(spi_confs) / sizeof(spi_confs[0]))
+#define SPI_NUMOF ARRAY_SIZE(spi_confs)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/f4vi1/include/periph_conf.h b/boards/f4vi1/include/periph_conf.h
index dceee5c06d..e28110591d 100644
--- a/boards/f4vi1/include/periph_conf.h
+++ b/boards/f4vi1/include/periph_conf.h
@@ -52,7 +52,7 @@ static const timer_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tim2
 #define TIMER_1_ISR         isr_tim5
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -79,7 +79,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_usart6)
 #define UART_0_DMA_ISR      (isr_dma2_stream6)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/feather-m0/include/periph_conf.h b/boards/feather-m0/include/periph_conf.h
index 80a9212368..7ea8c0fd1d 100644
--- a/boards/feather-m0/include/periph_conf.h
+++ b/boards/feather-m0/include/periph_conf.h
@@ -115,7 +115,7 @@ static const tc32_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tc3
 #define TIMER_1_ISR         isr_tc4
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -138,7 +138,7 @@ static const uart_conf_t uart_config[] = {
 /* interrupt function name mapping */
 #define UART_0_ISR          isr_sercom0
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -225,7 +225,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -243,7 +243,7 @@ static const i2c_conf_t i2c_config[] = {
         .flags    = I2C_FLAG_NONE
      }
 };
-#define I2C_NUMOF          (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF          ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
diff --git a/boards/firefly/include/periph_conf.h b/boards/firefly/include/periph_conf.h
index ef64c90bf0..9e46ca6aec 100644
--- a/boards/firefly/include/periph_conf.h
+++ b/boards/firefly/include/periph_conf.h
@@ -70,7 +70,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -86,7 +86,7 @@ static const adc_conf_t adc_config[] = {
     GPIO_PIN(PORT_A, 2),    /**< GPIO_PA2 = ADC3_PIN */
 };
 
-#define ADC_NUMOF           (sizeof(adc_config) / sizeof(adc_config[0]))
+#define ADC_NUMOF           ARRAY_SIZE(adc_config)
 /** @} */
 
 
diff --git a/boards/fox/include/periph_conf.h b/boards/fox/include/periph_conf.h
index 5d581a1401..97e15a8020 100644
--- a/boards/fox/include/periph_conf.h
+++ b/boards/fox/include/periph_conf.h
@@ -83,7 +83,7 @@ static const timer_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tim2
 #define TIMER_1_ISR         isr_tim3
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -112,7 +112,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_usart2)
 #define UART_1_ISR          (isr_usart1)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -151,7 +151,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -188,7 +188,7 @@ static const i2c_conf_t i2c_config[] = {
 
 #define I2C_0_ISR           isr_i2c1_ev
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/frdm-k22f/include/periph_conf.h b/boards/frdm-k22f/include/periph_conf.h
index 98070ec367..8963e6a535 100644
--- a/boards/frdm-k22f/include/periph_conf.h
+++ b/boards/frdm-k22f/include/periph_conf.h
@@ -132,7 +132,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_uart1_rx_tx)
 #define UART_1_ISR          (isr_uart0_rx_tx)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -159,7 +159,7 @@ static const adc_conf_t adc_config[] = {
     [ 9] = { .dev = ADC0, .pin = GPIO_UNDEF, .chan = 27, .avg = ADC_AVG_MAX },
 };
 
-#define ADC_NUMOF           (sizeof(adc_config) / sizeof(adc_config[0]))
+#define ADC_NUMOF           ARRAY_SIZE(adc_config)
 /*
  * K22F ADC reference settings:
  * 0: VREFH/VREFL external pin pair
@@ -186,7 +186,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 
@@ -251,7 +251,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 
@@ -271,7 +271,7 @@ static const i2c_conf_t i2c_config[] = {
         .sda_pcr = (PORT_PCR_MUX(2) | PORT_PCR_ODE_MASK),
     },
 };
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 #define I2C_0_ISR           (isr_i2c0)
 #define I2C_1_ISR           (isr_i2c1)
 /** @} */
diff --git a/boards/frdm-k64f/include/periph_conf.h b/boards/frdm-k64f/include/periph_conf.h
index 54770d93bf..2f14b75032 100644
--- a/boards/frdm-k64f/include/periph_conf.h
+++ b/boards/frdm-k64f/include/periph_conf.h
@@ -119,7 +119,7 @@ static const uart_conf_t uart_config[] = {
 
 #define UART_0_ISR          (isr_uart0_rx_tx)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -155,7 +155,7 @@ static const adc_conf_t adc_config[] = {
     [19] = { .dev = ADC0, .pin = GPIO_UNDEF, .chan = 27, .avg = ADC_AVG_MAX },
 };
 
-#define ADC_NUMOF           (sizeof(adc_config) / sizeof(adc_config[0]))
+#define ADC_NUMOF           ARRAY_SIZE(adc_config)
 /*
  * K64F ADC reference settings:
  * 0: VREFH/VREFL external pin pair
@@ -183,7 +183,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 
@@ -248,7 +248,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 
@@ -268,7 +268,7 @@ static const i2c_conf_t i2c_config[] = {
         .sda_pcr = (PORT_PCR_MUX(5) | PORT_PCR_ODE_MASK),
     },
 };
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 #define I2C_0_ISR           (isr_i2c0)
 #define I2C_1_ISR           (isr_i2c1)
 /** @} */
diff --git a/boards/frdm-kw41z/include/periph_conf.h b/boards/frdm-kw41z/include/periph_conf.h
index 9fcb7f811c..ed054ea0b6 100644
--- a/boards/frdm-kw41z/include/periph_conf.h
+++ b/boards/frdm-kw41z/include/periph_conf.h
@@ -64,7 +64,7 @@ static const spi_conf_t spi_config[] = {
         .simmask  = SIM_SCGC6_SPI1_MASK
     }
 };
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -92,7 +92,7 @@ static const adc_conf_t adc_config[] = {
     /* internal: DCDC divided battery level */
     [ 6] = { .dev = ADC0, .pin = GPIO_UNDEF, .chan = 23, .avg = ADC_AVG_MAX },
 };
-#define ADC_NUMOF           (sizeof(adc_config) / sizeof(adc_config[0]))
+#define ADC_NUMOF           ARRAY_SIZE(adc_config)
 /*
  * KW41Z ADC reference settings:
  * 0: VREFH external pin or VREF_OUT 1.2 V signal (if VREF module is enabled)
diff --git a/boards/hamilton/include/periph_conf.h b/boards/hamilton/include/periph_conf.h
index c1bf3c6c80..4b81db4e8c 100644
--- a/boards/hamilton/include/periph_conf.h
+++ b/boards/hamilton/include/periph_conf.h
@@ -150,7 +150,7 @@ static const tc32_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tc3
 #define TIMER_1_ISR         isr_tc4
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -230,7 +230,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -248,7 +248,7 @@ static const i2c_conf_t i2c_config[] = {
         .flags    = I2C_FLAG_NONE
      }
 };
-#define I2C_NUMOF          (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF          ARRAY_SIZE(i2c_config)
 
 /**
  * @name Random Number Generator configuration
diff --git a/boards/i-nucleo-lrwan1/include/periph_conf.h b/boards/i-nucleo-lrwan1/include/periph_conf.h
index 1b867497d6..a7fd36791f 100644
--- a/boards/i-nucleo-lrwan1/include/periph_conf.h
+++ b/boards/i-nucleo-lrwan1/include/periph_conf.h
@@ -49,7 +49,7 @@ static const uart_conf_t uart_config[] = {
 
 #define UART_0_ISR          (isr_rng_lpuart1)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -89,7 +89,7 @@ static const spi_conf_t spi_config[] = {
     },
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -112,7 +112,7 @@ static const i2c_conf_t i2c_config[] = {
 
 #define I2C_0_ISR           isr_i2c1
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/ikea-tradfri/include/periph_conf.h b/boards/ikea-tradfri/include/periph_conf.h
index fbb133e4fa..74974dc698 100644
--- a/boards/ikea-tradfri/include/periph_conf.h
+++ b/boards/ikea-tradfri/include/periph_conf.h
@@ -27,11 +27,6 @@
 extern "C" {
 #endif
 
-/**
- * @brief   Internal macro to calculate *_NUMOF based on config.
- */
-#define PERIPH_NUMOF(config)    (sizeof(config) / sizeof(config[0]))
-
 /**
  * @name    Clock configuration
  * @{
@@ -88,7 +83,7 @@ static const spi_dev_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           PERIPH_NUMOF(spi_config)
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -111,7 +106,7 @@ static const timer_conf_t timer_config[] = {
     }
 };
 
-#define TIMER_NUMOF         PERIPH_NUMOF(timer_config)
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 #define TIMER_0_ISR         isr_timer1
 /** @} */
 
@@ -134,7 +129,7 @@ static const uart_conf_t uart_config[] = {
     }
 };
 
-#define UART_NUMOF          PERIPH_NUMOF(uart_config)
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 #define UART_0_ISR_RX       isr_usart0_rx
 /** @} */
 
diff --git a/boards/iotlab-a8-m3/include/periph_conf.h b/boards/iotlab-a8-m3/include/periph_conf.h
index 4c4446ac96..0b31b05493 100644
--- a/boards/iotlab-a8-m3/include/periph_conf.h
+++ b/boards/iotlab-a8-m3/include/periph_conf.h
@@ -43,7 +43,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/iotlab-m3/include/periph_conf.h b/boards/iotlab-m3/include/periph_conf.h
index e912a9bb13..daeaed94bb 100644
--- a/boards/iotlab-m3/include/periph_conf.h
+++ b/boards/iotlab-m3/include/periph_conf.h
@@ -49,7 +49,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/limifrog-v1/include/periph_conf.h b/boards/limifrog-v1/include/periph_conf.h
index 39cc19fcb5..b85d36527d 100644
--- a/boards/limifrog-v1/include/periph_conf.h
+++ b/boards/limifrog-v1/include/periph_conf.h
@@ -65,7 +65,7 @@ static const timer_conf_t timer_config[] = {
 
 #define TIMER_0_ISR         (isr_tim5)
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -98,7 +98,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_usart3)
 #define UART_1_ISR          (isr_usart1)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -148,7 +148,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -185,7 +185,7 @@ static const i2c_conf_t i2c_config[] = {
 #define I2C_0_ISR           isr_i2c1_ev
 #define I2C_1_ISR           isr_i2c2_ev
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/lobaro-lorabox/include/periph_conf.h b/boards/lobaro-lorabox/include/periph_conf.h
index 38f0c51887..0bebb1f232 100644
--- a/boards/lobaro-lorabox/include/periph_conf.h
+++ b/boards/lobaro-lorabox/include/periph_conf.h
@@ -101,7 +101,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_usart1)
 #define UART_1_ISR          (isr_usart2)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -158,7 +158,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -182,7 +182,7 @@ static const i2c_conf_t i2c_config[] = {
 
 #define I2C_0_ISR           isr_i2c1_ev
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/lsn50/include/periph_conf.h b/boards/lsn50/include/periph_conf.h
index 889dbdeae6..cebe8d2d7b 100644
--- a/boards/lsn50/include/periph_conf.h
+++ b/boards/lsn50/include/periph_conf.h
@@ -46,7 +46,7 @@ static const dma_conf_t dma_config[] = {
 #define DMA_SHARED_ISR_1            isr_dma1_channel4_5_6_7
 #define DMA_SHARED_ISR_1_STREAMS    { 2, 3, 4 } /* Indexes 2, 3 and 4 of dma_config share the same isr */
 
-#define DMA_NUMOF           (sizeof(dma_config) / sizeof(dma_config[0]))
+#define DMA_NUMOF           ARRAY_SIZE(dma_config)
 #endif
 /** @} */
 
@@ -92,7 +92,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_usart1)
 #define UART_1_ISR          (isr_usart2)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -138,7 +138,7 @@ static const spi_conf_t spi_config[] = {
     },
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -161,7 +161,7 @@ static const i2c_conf_t i2c_config[] = {
 
 #define I2C_0_ISR           isr_i2c1
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/maple-mini/include/periph_conf.h b/boards/maple-mini/include/periph_conf.h
index 24ca083380..a5e2bdd944 100644
--- a/boards/maple-mini/include/periph_conf.h
+++ b/boards/maple-mini/include/periph_conf.h
@@ -83,7 +83,7 @@ static const timer_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tim2
 #define TIMER_1_ISR         isr_tim3
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -121,7 +121,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          isr_usart1
 #define UART_2_ISR          isr_usart3
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -154,7 +154,7 @@ static const i2c_conf_t i2c_config[] = {
 #define I2C_0_ISR           isr_i2c1_ev
 #define I2C_1_ISR           isr_i2c2_ev
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
@@ -205,7 +205,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/microbit/include/periph_conf.h b/boards/microbit/include/periph_conf.h
index 9ff4c0da50..75fc502d9a 100644
--- a/boards/microbit/include/periph_conf.h
+++ b/boards/microbit/include/periph_conf.h
@@ -53,7 +53,7 @@ static const i2c_conf_t i2c_config[] = {
     }
 };
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/msbiot/include/periph_conf.h b/boards/msbiot/include/periph_conf.h
index b083dbc0bb..43d7689d5a 100644
--- a/boards/msbiot/include/periph_conf.h
+++ b/boards/msbiot/include/periph_conf.h
@@ -51,7 +51,7 @@ static const timer_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tim2
 #define TIMER_1_ISR         isr_tim5
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -71,7 +71,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -98,7 +98,7 @@ static const dac_conf_t dac_config[] = {
     { .pin = GPIO_PIN(PORT_A,  5), .chan = 1 }
 };
 
-#define DAC_NUMOF           (sizeof(dac_config) / sizeof(dac_config[0]))
+#define DAC_NUMOF           ARRAY_SIZE(dac_config)
 /** @} */
 
 /**
@@ -159,7 +159,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_2_DMA_ISR      (isr_dma1_stream3)
 
 /* deduct number of defined UART interfaces */
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -179,7 +179,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -203,7 +203,7 @@ static const i2c_conf_t i2c_config[] = {
 
 #define I2C_0_ISR           isr_i2c1_ev
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/mulle/include/periph_conf.h b/boards/mulle/include/periph_conf.h
index 491cf2ca89..5ff6e02405 100644
--- a/boards/mulle/include/periph_conf.h
+++ b/boards/mulle/include/periph_conf.h
@@ -156,7 +156,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_uart0_rx_tx)
 #define UART_1_ISR          (isr_uart1_rx_tx)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -202,7 +202,7 @@ static const adc_conf_t adc_config[] = {
     [16] = { .dev = ADC1, .pin = GPIO_PIN(PORT_C, 11), .chan =  7, .avg = ADC_AVG_MAX },
 };
 
-#define ADC_NUMOF           (sizeof(adc_config) / sizeof(adc_config[0]))
+#define ADC_NUMOF           ARRAY_SIZE(adc_config)
 /*
  * K60D ADC reference settings:
  * 0: VREFH/VREFL external pin pair
@@ -224,7 +224,7 @@ static const dac_conf_t dac_config[] = {
     }
 };
 
-#define DAC_NUMOF           (sizeof(dac_config) / sizeof(dac_config[0]))
+#define DAC_NUMOF           ARRAY_SIZE(dac_config)
 /** @} */
 
 /**
@@ -256,7 +256,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -335,7 +335,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -354,7 +354,7 @@ static const i2c_conf_t i2c_config[] = {
         .sda_pcr = (PORT_PCR_MUX(2) | PORT_PCR_ODE_MASK),
     },
 };
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 #define I2C_0_ISR           (isr_i2c0)
 #define I2C_1_ISR           (isr_i2c1)
 /** @} */
diff --git a/boards/native/include/board.h b/boards/native/include/board.h
index 1d9061c2d7..d4cf336c5a 100644
--- a/boards/native/include/board.h
+++ b/boards/native/include/board.h
@@ -180,7 +180,7 @@ static const motor_driver_config_t motor_driver_config[] = {
     },
 };
 
-#define MOTOR_DRIVER_NUMOF           (sizeof(motor_driver_config) / sizeof(motor_driver_config[0]))
+#define MOTOR_DRIVER_NUMOF           ARRAY_SIZE(motor_driver_config)
 /** @} */
 
 #endif /* __cplusplus */
diff --git a/boards/nrf51dk/include/periph_conf.h b/boards/nrf51dk/include/periph_conf.h
index 3b5b9a9b13..e8d9d38447 100644
--- a/boards/nrf51dk/include/periph_conf.h
+++ b/boards/nrf51dk/include/periph_conf.h
@@ -54,7 +54,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -71,7 +71,7 @@ static const i2c_conf_t i2c_config[] = {
     }
 };
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nrf52840-mdk/include/periph_conf.h b/boards/nrf52840-mdk/include/periph_conf.h
index 8bf2448f7a..b130305deb 100644
--- a/boards/nrf52840-mdk/include/periph_conf.h
+++ b/boards/nrf52840-mdk/include/periph_conf.h
@@ -48,7 +48,7 @@ static const uart_conf_t uart_config[] = {
 
 #define UART_0_ISR          (isr_uart0)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nrf52840dk/include/periph_conf.h b/boards/nrf52840dk/include/periph_conf.h
index f013fe8465..67b37ff256 100644
--- a/boards/nrf52840dk/include/periph_conf.h
+++ b/boards/nrf52840dk/include/periph_conf.h
@@ -38,7 +38,7 @@ static const spi_conf_t spi_config[] = {
         .miso = GPIO_PIN(1, 14),
     }
 };
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -67,7 +67,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_uart0)
 #define UART_1_ISR          (isr_uarte1)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nrf52dk/include/periph_conf.h b/boards/nrf52dk/include/periph_conf.h
index e41e3b4ba7..581f1bd9ff 100644
--- a/boards/nrf52dk/include/periph_conf.h
+++ b/boards/nrf52dk/include/periph_conf.h
@@ -40,7 +40,7 @@ static const spi_conf_t spi_config[] = {
         .miso = GPIO_PIN(0, 24),
     }
 };
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/nrf6310/include/periph_conf.h b/boards/nrf6310/include/periph_conf.h
index a8a766bf2f..b154c8f927 100644
--- a/boards/nrf6310/include/periph_conf.h
+++ b/boards/nrf6310/include/periph_conf.h
@@ -66,7 +66,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nucleo-f030r8/include/periph_conf.h b/boards/nucleo-f030r8/include/periph_conf.h
index b02f40ad6f..860a2c89ed 100644
--- a/boards/nucleo-f030r8/include/periph_conf.h
+++ b/boards/nucleo-f030r8/include/periph_conf.h
@@ -71,7 +71,7 @@ static const timer_conf_t timer_config[] = {
 
 #define TIMER_0_ISR         (isr_tim1_cc)
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -104,7 +104,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_usart2)
 #define UART_1_ISR          (isr_usart1)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -134,7 +134,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -184,7 +184,7 @@ static const spi_conf_t spi_config[] = {
     },
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/nucleo-f031k6/include/periph_conf.h b/boards/nucleo-f031k6/include/periph_conf.h
index 8a981f615b..53f1b81fb5 100644
--- a/boards/nucleo-f031k6/include/periph_conf.h
+++ b/boards/nucleo-f031k6/include/periph_conf.h
@@ -74,7 +74,7 @@ static const uart_conf_t uart_config[] = {
 
 #define UART_0_ISR          (isr_usart1)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -114,7 +114,7 @@ static const pwm_conf_t pwm_config[] = {
     },
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -154,7 +154,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/nucleo-f042k6/include/periph_conf.h b/boards/nucleo-f042k6/include/periph_conf.h
index 201ccad0b7..18d14eaa50 100644
--- a/boards/nucleo-f042k6/include/periph_conf.h
+++ b/boards/nucleo-f042k6/include/periph_conf.h
@@ -84,7 +84,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_usart2)
 #define UART_1_ISR          (isr_usart1)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -124,7 +124,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -164,7 +164,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/nucleo-f070rb/include/periph_conf.h b/boards/nucleo-f070rb/include/periph_conf.h
index e36395babc..7f63d55329 100644
--- a/boards/nucleo-f070rb/include/periph_conf.h
+++ b/boards/nucleo-f070rb/include/periph_conf.h
@@ -73,7 +73,7 @@ static const timer_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tim1_cc
 
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -117,7 +117,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          (isr_usart1)
 #define UART_2_ISR          (isr_usart3_8)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -147,7 +147,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
diff --git a/boards/nucleo-f072rb/include/periph_conf.h b/boards/nucleo-f072rb/include/periph_conf.h
index 6dd8aa188e..37bda70182 100644
--- a/boards/nucleo-f072rb/include/periph_conf.h
+++ b/boards/nucleo-f072rb/include/periph_conf.h
@@ -71,7 +71,7 @@ static const timer_conf_t timer_config[] = {
 
 #define TIMER_0_ISR         isr_tim1_cc
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -115,7 +115,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          (isr_usart1)
 #define UART_2_ISR          (isr_usart3_8)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -155,7 +155,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -205,7 +205,7 @@ static const spi_conf_t spi_config[] = {
     },
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/nucleo-f091rc/include/periph_conf.h b/boards/nucleo-f091rc/include/periph_conf.h
index a6a94c792d..cfd67f1d37 100644
--- a/boards/nucleo-f091rc/include/periph_conf.h
+++ b/boards/nucleo-f091rc/include/periph_conf.h
@@ -67,7 +67,7 @@ static const dma_conf_t dma_config[] = {
 #define DMA_SHARED_ISR_0            isr_dma1_ch2_3_dma2_ch1_2
 #define DMA_SHARED_ISR_0_STREAMS    { 0, 1 } /* Indexes 0 and 1 of dma_config share the same isr */
 
-#define DMA_NUMOF           (sizeof(dma_config) / sizeof(dma_config[0]))
+#define DMA_NUMOF           ARRAY_SIZE(dma_config)
 #endif
 
 /**
@@ -86,7 +86,7 @@ static const timer_conf_t timer_config[] = {
 
 #define TIMER_0_ISR         isr_tim1_cc
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -142,7 +142,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          (isr_usart1)
 #define UART_2_ISR          (isr_usart3_8)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 
@@ -189,7 +189,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -219,7 +219,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
diff --git a/boards/nucleo-f103rb/include/periph_conf.h b/boards/nucleo-f103rb/include/periph_conf.h
index b73bd1280b..c90fa4cef2 100644
--- a/boards/nucleo-f103rb/include/periph_conf.h
+++ b/boards/nucleo-f103rb/include/periph_conf.h
@@ -78,7 +78,7 @@ static const timer_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tim2
 #define TIMER_1_ISR         isr_tim3
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -116,7 +116,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          (isr_usart1)
 #define UART_2_ISR          (isr_usart3)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -165,7 +165,7 @@ static const i2c_conf_t i2c_config[] = {
 #define I2C_0_ISR           isr_i2c1_ev
 #define I2C_1_ISR           isr_i2c2_ev
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
@@ -213,7 +213,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nucleo-f207zg/include/periph_conf.h b/boards/nucleo-f207zg/include/periph_conf.h
index 5d7e8163cf..5c55811445 100644
--- a/boards/nucleo-f207zg/include/periph_conf.h
+++ b/boards/nucleo-f207zg/include/periph_conf.h
@@ -50,7 +50,7 @@ static const dma_conf_t dma_config[] = {
 #define DMA_4_ISR  isr_dma2_stream6
 #define DMA_5_ISR  isr_dma1_stream6
 
-#define DMA_NUMOF           (sizeof(dma_config) / sizeof(dma_config[0]))
+#define DMA_NUMOF           ARRAY_SIZE(dma_config)
 #endif
 /** @} */
 
@@ -81,7 +81,7 @@ static const pwm_conf_t pwm_config[] = {
     },
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -108,7 +108,7 @@ static const timer_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tim2
 #define TIMER_1_ISR         isr_tim5
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -164,7 +164,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          (isr_usart6)
 #define UART_2_ISR          (isr_usart2)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -226,7 +226,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/nucleo-f302r8/include/periph_conf.h b/boards/nucleo-f302r8/include/periph_conf.h
index 006e22f3f0..2b79633a95 100644
--- a/boards/nucleo-f302r8/include/periph_conf.h
+++ b/boards/nucleo-f302r8/include/periph_conf.h
@@ -100,7 +100,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          (isr_usart1)
 #define UART_2_ISR          (isr_usart3)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -120,7 +120,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -160,7 +160,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -197,7 +197,7 @@ static const i2c_conf_t i2c_config[] = {
 #define I2C_0_ISR           isr_i2c1_er
 #define I2C_1_ISR           isr_i2c3_er
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nucleo-f303k8/include/periph_conf.h b/boards/nucleo-f303k8/include/periph_conf.h
index 74e162dc61..b6c2696563 100644
--- a/boards/nucleo-f303k8/include/periph_conf.h
+++ b/boards/nucleo-f303k8/include/periph_conf.h
@@ -85,7 +85,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_usart2)
 #define UART_1_ISR          (isr_usart1)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -115,7 +115,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -155,7 +155,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nucleo-f303re/include/periph_conf.h b/boards/nucleo-f303re/include/periph_conf.h
index 9b8f0155e4..190b5246a4 100644
--- a/boards/nucleo-f303re/include/periph_conf.h
+++ b/boards/nucleo-f303re/include/periph_conf.h
@@ -98,7 +98,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          (isr_usart1)
 #define UART_2_ISR          (isr_usart3)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -118,7 +118,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -178,7 +178,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -215,7 +215,7 @@ static const i2c_conf_t i2c_config[] = {
 #define I2C_0_ISR           isr_i2c1_er
 #define I2C_1_ISR           isr_i2c3_er
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nucleo-f303ze/include/periph_conf.h b/boards/nucleo-f303ze/include/periph_conf.h
index d602951176..b6d5221def 100644
--- a/boards/nucleo-f303ze/include/periph_conf.h
+++ b/boards/nucleo-f303ze/include/periph_conf.h
@@ -111,7 +111,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_2_ISR          (isr_usart2)
 #define UART_2_DMA_ISR      (isr_dma1_stream4)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -141,7 +141,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -181,7 +181,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nucleo-f334r8/include/periph_conf.h b/boards/nucleo-f334r8/include/periph_conf.h
index c3af0285dd..b5e938a540 100644
--- a/boards/nucleo-f334r8/include/periph_conf.h
+++ b/boards/nucleo-f334r8/include/periph_conf.h
@@ -97,7 +97,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          (isr_usart1)
 #define UART_2_ISR          (isr_usart3)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -117,7 +117,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -157,7 +157,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nucleo-f401re/include/periph_conf.h b/boards/nucleo-f401re/include/periph_conf.h
index 378f7762de..054eba67eb 100644
--- a/boards/nucleo-f401re/include/periph_conf.h
+++ b/boards/nucleo-f401re/include/periph_conf.h
@@ -84,7 +84,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_2_ISR          (isr_usart6)
 #define UART_2_DMA_ISR      (isr_dma1_stream6)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -104,7 +104,7 @@ static const pwm_conf_t pwm_config[] = {
     },
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -137,7 +137,7 @@ static const qdec_conf_t qdec_config[] = {
 #define QDEC_0_ISR         isr_tim3
 #define QDEC_1_ISR         isr_tim4
 
-#define QDEC_NUMOF           (sizeof(qdec_config) / sizeof(qdec_config[0]))
+#define QDEC_NUMOF           ARRAY_SIZE(qdec_config)
 /** @} */
 
 /**
@@ -197,7 +197,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/nucleo-f410rb/include/periph_conf.h b/boards/nucleo-f410rb/include/periph_conf.h
index 13f6d80514..66f769232b 100644
--- a/boards/nucleo-f410rb/include/periph_conf.h
+++ b/boards/nucleo-f410rb/include/periph_conf.h
@@ -86,7 +86,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_2_DMA_ISR      (isr_dma2_stream7)
 
 /* deduct number of defined UART interfaces */
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -126,7 +126,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/nucleo-f411re/include/periph_conf.h b/boards/nucleo-f411re/include/periph_conf.h
index fe29aec112..d281189f6c 100644
--- a/boards/nucleo-f411re/include/periph_conf.h
+++ b/boards/nucleo-f411re/include/periph_conf.h
@@ -86,7 +86,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_2_DMA_ISR      isr_dma1_stream6
 
 /* deduct number of defined UART interfaces */
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /** @name    PWM configuration
@@ -115,7 +115,7 @@ static const pwm_conf_t pwm_config[] = {
     },
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -155,7 +155,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/nucleo-f412zg/include/periph_conf.h b/boards/nucleo-f412zg/include/periph_conf.h
index d8b0660293..757c24529e 100644
--- a/boards/nucleo-f412zg/include/periph_conf.h
+++ b/boards/nucleo-f412zg/include/periph_conf.h
@@ -86,7 +86,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_2_ISR          (isr_usart2)
 #define UART_2_DMA_ISR      (isr_dma1_stream4)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -116,7 +116,7 @@ static const pwm_conf_t pwm_config[] = {
     },
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -156,7 +156,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/nucleo-f413zh/include/periph_conf.h b/boards/nucleo-f413zh/include/periph_conf.h
index a94e06ad8c..a025f0bb5c 100644
--- a/boards/nucleo-f413zh/include/periph_conf.h
+++ b/boards/nucleo-f413zh/include/periph_conf.h
@@ -49,7 +49,7 @@ static const dma_conf_t dma_config[] = {
 #define DMA_3_ISR  isr_dma2_stream2
 #define DMA_4_ISR  isr_dma2_stream0
 
-#define DMA_NUMOF           (sizeof(dma_config) / sizeof(dma_config[0]))
+#define DMA_NUMOF           ARRAY_SIZE(dma_config)
 #endif
 /** @} */
 
@@ -109,7 +109,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_2_ISR          (isr_usart2)
 #define UART_2_DMA_ISR      (isr_dma1_stream4)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -139,7 +139,7 @@ static const pwm_conf_t pwm_config[] = {
     },
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -185,7 +185,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/nucleo-f429zi/include/periph_conf.h b/boards/nucleo-f429zi/include/periph_conf.h
index cfe91fd337..c73b3459f0 100644
--- a/boards/nucleo-f429zi/include/periph_conf.h
+++ b/boards/nucleo-f429zi/include/periph_conf.h
@@ -85,7 +85,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_2_ISR          (isr_usart2)
 #define UART_2_DMA_ISR      (isr_dma1_stream4)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -115,7 +115,7 @@ static const pwm_conf_t pwm_config[] = {
     },
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -135,7 +135,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/nucleo-f446re/include/periph_conf.h b/boards/nucleo-f446re/include/periph_conf.h
index ca41c7ab24..6a73b74a14 100644
--- a/boards/nucleo-f446re/include/periph_conf.h
+++ b/boards/nucleo-f446re/include/periph_conf.h
@@ -85,7 +85,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_2_ISR          (isr_usart3)
 #define UART_2_DMA_ISR      (isr_dma1_stream5)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -115,7 +115,7 @@ static const pwm_conf_t pwm_config[] = {
     },
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -148,7 +148,7 @@ static const qdec_conf_t qdec_config[] = {
 #define QDEC_0_ISR         isr_tim3
 #define QDEC_1_ISR         isr_tim4
 
-#define QDEC_NUMOF           (sizeof(qdec_config) / sizeof(qdec_config[0]))
+#define QDEC_NUMOF           ARRAY_SIZE(qdec_config)
 /** @} */
 
 /**
@@ -191,7 +191,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/nucleo-f446ze/include/periph_conf.h b/boards/nucleo-f446ze/include/periph_conf.h
index f126625bf0..240d21db6f 100644
--- a/boards/nucleo-f446ze/include/periph_conf.h
+++ b/boards/nucleo-f446ze/include/periph_conf.h
@@ -85,7 +85,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_2_ISR          (isr_usart2)
 #define UART_2_DMA_ISR      (isr_dma1_stream4)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -115,7 +115,7 @@ static const pwm_conf_t pwm_config[] = {
     },
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -135,7 +135,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nucleo-f722ze/include/periph_conf.h b/boards/nucleo-f722ze/include/periph_conf.h
index 252ed02403..3869d9bf1b 100644
--- a/boards/nucleo-f722ze/include/periph_conf.h
+++ b/boards/nucleo-f722ze/include/periph_conf.h
@@ -85,7 +85,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_2_ISR          (isr_usart2)
 #define UART_2_DMA_ISR      (isr_dma1_stream4)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nucleo-f746zg/include/periph_conf.h b/boards/nucleo-f746zg/include/periph_conf.h
index bb0bbc31cf..34f92f1a4f 100644
--- a/boards/nucleo-f746zg/include/periph_conf.h
+++ b/boards/nucleo-f746zg/include/periph_conf.h
@@ -85,7 +85,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_2_ISR          (isr_usart2)
 #define UART_2_DMA_ISR      (isr_dma1_stream4)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nucleo-f767zi/include/periph_conf.h b/boards/nucleo-f767zi/include/periph_conf.h
index b5e1aff673..1c73de25c0 100644
--- a/boards/nucleo-f767zi/include/periph_conf.h
+++ b/boards/nucleo-f767zi/include/periph_conf.h
@@ -47,7 +47,7 @@ static const dma_conf_t dma_config[] = {
 #define DMA_2_ISR  isr_dma1_stream6
 #define DMA_3_ISR  isr_dma2_stream0
 
-#define DMA_NUMOF           (sizeof(dma_config) / sizeof(dma_config[0]))
+#define DMA_NUMOF           ARRAY_SIZE(dma_config)
 #endif
 /** @} */
 
@@ -104,7 +104,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          (isr_usart6)
 #define UART_2_ISR          (isr_usart2)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -137,7 +137,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/nucleo-l031k6/include/periph_conf.h b/boards/nucleo-l031k6/include/periph_conf.h
index 3bc471f2d6..d6c8a05cf4 100644
--- a/boards/nucleo-l031k6/include/periph_conf.h
+++ b/boards/nucleo-l031k6/include/periph_conf.h
@@ -51,7 +51,7 @@ static const uart_conf_t uart_config[] = {
 
 #define UART_0_ISR          (isr_usart2)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -71,7 +71,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -108,7 +108,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/nucleo-l053r8/include/periph_conf.h b/boards/nucleo-l053r8/include/periph_conf.h
index 9c582446a1..03c8f03fa5 100644
--- a/boards/nucleo-l053r8/include/periph_conf.h
+++ b/boards/nucleo-l053r8/include/periph_conf.h
@@ -64,7 +64,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_usart2)
 #define UART_1_ISR          (isr_usart1)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -84,7 +84,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -124,7 +124,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nucleo-l073rz/include/periph_conf.h b/boards/nucleo-l073rz/include/periph_conf.h
index 884413c6b4..9b19df328d 100644
--- a/boards/nucleo-l073rz/include/periph_conf.h
+++ b/boards/nucleo-l073rz/include/periph_conf.h
@@ -82,7 +82,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_2_ISR          (isr_rng_lpuart1)
 #endif
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -102,7 +102,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -142,7 +142,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -193,7 +193,7 @@ static const i2c_conf_t i2c_config[] = {
 #define I2C_0_ISR           isr_i2c1
 #define I2C_1_ISR           isr_i2c2
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nucleo-l152re/include/periph_conf.h b/boards/nucleo-l152re/include/periph_conf.h
index 4b02fb1f3a..f20fc1d65e 100644
--- a/boards/nucleo-l152re/include/periph_conf.h
+++ b/boards/nucleo-l152re/include/periph_conf.h
@@ -78,7 +78,7 @@ static const dma_conf_t dma_config[] = {
 #define DMA_2_ISR  isr_dma1_ch7
 #define DMA_3_ISR  isr_dma1_ch4
 
-#define DMA_NUMOF           (sizeof(dma_config) / sizeof(dma_config[0]))
+#define DMA_NUMOF           ARRAY_SIZE(dma_config)
 #endif
 /** @} */
 
@@ -135,7 +135,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          (isr_usart1)
 #define UART_2_ISR          (isr_usart3)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -165,7 +165,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -211,7 +211,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -248,7 +248,7 @@ static const i2c_conf_t i2c_config[] = {
 #define I2C_0_ISR           isr_i2c1_ev
 #define I2C_1_ISR           isr_i2c2_ev
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
@@ -276,7 +276,7 @@ static const dac_conf_t dac_config[] = {
     { .pin = GPIO_PIN(PORT_A,  5), .chan = 1 }
 };
 
-#define DAC_NUMOF           (sizeof(dac_config) / sizeof(dac_config[0]))
+#define DAC_NUMOF           ARRAY_SIZE(dac_config)
 /** @} */
 
 
diff --git a/boards/nucleo-l432kc/include/periph_conf.h b/boards/nucleo-l432kc/include/periph_conf.h
index d383ff96e1..ca7d9f5945 100644
--- a/boards/nucleo-l432kc/include/periph_conf.h
+++ b/boards/nucleo-l432kc/include/periph_conf.h
@@ -107,7 +107,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_usart2)
 #define UART_1_ISR          (isr_usart1)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -127,7 +127,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -167,7 +167,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nucleo-l433rc/include/periph_conf.h b/boards/nucleo-l433rc/include/periph_conf.h
index 16670b4d89..13b3a94f42 100644
--- a/boards/nucleo-l433rc/include/periph_conf.h
+++ b/boards/nucleo-l433rc/include/periph_conf.h
@@ -120,7 +120,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_lpuart1)
 #define UART_1_ISR          (isr_usart1)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -140,7 +140,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -180,7 +180,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -203,7 +203,7 @@ static const i2c_conf_t i2c_config[] = {
 
 #define I2C_0_ISR           isr_i2c1_er
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nucleo-l452re/include/periph_conf.h b/boards/nucleo-l452re/include/periph_conf.h
index 47b0bc275d..5bc7252fd8 100644
--- a/boards/nucleo-l452re/include/periph_conf.h
+++ b/boards/nucleo-l452re/include/periph_conf.h
@@ -121,7 +121,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_usart2)
 #define UART_1_ISR          (isr_usart3)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -141,7 +141,7 @@ static const pwm_conf_t pwm_config[] = {
     },
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -181,7 +181,7 @@ static const spi_conf_t spi_config[] = {
     },
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nucleo-l476rg/include/periph_conf.h b/boards/nucleo-l476rg/include/periph_conf.h
index 92347d218c..a61bb2ca1e 100644
--- a/boards/nucleo-l476rg/include/periph_conf.h
+++ b/boards/nucleo-l476rg/include/periph_conf.h
@@ -105,7 +105,7 @@ static const dma_conf_t dma_config[] = {
 #define DMA_2_ISR  isr_dma1_channel4
 #define DMA_3_ISR  isr_dma1_channel7
 
-#define DMA_NUMOF           (sizeof(dma_config) / sizeof(dma_config[0]))
+#define DMA_NUMOF           ARRAY_SIZE(dma_config)
 #endif /* MODULE_PERIPH_DMA */
 /** @} */
 
@@ -126,7 +126,7 @@ static const timer_conf_t timer_config[] = {
 
 #define TIMER_0_ISR         isr_tim5
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -188,7 +188,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          (isr_usart3)
 #define UART_2_ISR          (isr_usart1)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -228,7 +228,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -274,7 +274,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/nucleo-l496zg/include/periph_conf.h b/boards/nucleo-l496zg/include/periph_conf.h
index 528bb72a57..ee75247367 100644
--- a/boards/nucleo-l496zg/include/periph_conf.h
+++ b/boards/nucleo-l496zg/include/periph_conf.h
@@ -106,7 +106,7 @@ static const timer_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tim2
 #define TIMER_1_ISR         isr_tim5
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -148,7 +148,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          (isr_usart3)
 #define UART_1_DMA_ISR      (isr_dma1_stream5)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -178,7 +178,7 @@ static const pwm_conf_t pwm_config[] = {
     },
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -218,7 +218,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nucleo-l4r5zi/include/periph_conf.h b/boards/nucleo-l4r5zi/include/periph_conf.h
index 093e5db5a2..fbf0a15588 100644
--- a/boards/nucleo-l4r5zi/include/periph_conf.h
+++ b/boards/nucleo-l4r5zi/include/periph_conf.h
@@ -84,7 +84,7 @@ static const timer_conf_t timer_config[] = {
 
 #define TIMER_0_ISR         isr_tim5
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -125,7 +125,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_lpuart1)
 #define UART_1_ISR          (isr_usart3)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -165,7 +165,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/nz32-sc151/include/periph_conf.h b/boards/nz32-sc151/include/periph_conf.h
index c9b6aa2b39..d2b6f87587 100644
--- a/boards/nz32-sc151/include/periph_conf.h
+++ b/boards/nz32-sc151/include/periph_conf.h
@@ -91,7 +91,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          (isr_usart2)
 #define UART_2_ISR          (isr_usart1)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -111,7 +111,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -171,7 +171,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -195,7 +195,7 @@ static const i2c_conf_t i2c_config[] = {
 
 #define I2C_0_ISR           isr_i2c1_ev
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
@@ -224,7 +224,7 @@ static const dac_conf_t dac_config[] = {
     { .pin = GPIO_PIN(PORT_A,  5), .chan = 1 }
 };
 
-#define DAC_NUMOF           (sizeof(dac_config) / sizeof(dac_config[0]))
+#define DAC_NUMOF           ARRAY_SIZE(dac_config)
 /** @} */
 
 
diff --git a/boards/opencm904/include/periph_conf.h b/boards/opencm904/include/periph_conf.h
index ffc9fe80f4..0541b7cae6 100644
--- a/boards/opencm904/include/periph_conf.h
+++ b/boards/opencm904/include/periph_conf.h
@@ -83,7 +83,7 @@ static const timer_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tim2
 #define TIMER_1_ISR         isr_tim3
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -121,7 +121,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          isr_usart1
 #define UART_2_ISR          isr_usart3
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/openmote-b/include/periph_conf.h b/boards/openmote-b/include/periph_conf.h
index 97b915a392..c6b53d18e9 100644
--- a/boards/openmote-b/include/periph_conf.h
+++ b/boards/openmote-b/include/periph_conf.h
@@ -63,7 +63,7 @@ static const timer_conf_t timer_config[] = {
     },
 };
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 #define TIMER_IRQ_PRIO      1
 /** @} */
 
@@ -83,7 +83,7 @@ static const adc_conf_t adc_config[] = {
 
 };
 
-#define ADC_NUMOF           (sizeof(adc_config) / sizeof(adc_config[0]))
+#define ADC_NUMOF           ARRAY_SIZE(adc_config)
 /** @} */
 
 /**
@@ -104,7 +104,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          isr_uart0
 
 /* macros common across all UARTs */
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -121,7 +121,7 @@ static const i2c_conf_t i2c_config[] = {
     },
 };
 
-#define I2C_NUMOF               (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF               ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
@@ -138,7 +138,7 @@ static const spi_conf_t spi_config[] = {
     },
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/openmote-cc2538/include/periph_conf.h b/boards/openmote-cc2538/include/periph_conf.h
index c82d63bb7d..29bc1d4175 100644
--- a/boards/openmote-cc2538/include/periph_conf.h
+++ b/boards/openmote-cc2538/include/periph_conf.h
@@ -61,7 +61,7 @@ static const timer_conf_t timer_config[] = {
     },
 };
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 #define TIMER_IRQ_PRIO      1
 /** @} */
 
@@ -79,7 +79,7 @@ static const adc_conf_t adc_config[] = {
     GPIO_PIN(0, 6), /**< GPIO_PA6 = ON_SLEEP_PIN */
 };
 
-#define ADC_NUMOF           (sizeof(adc_config) / sizeof(adc_config[0]))
+#define ADC_NUMOF           ARRAY_SIZE(adc_config)
 /** @} */
 
 /**
@@ -100,7 +100,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          isr_uart0
 
 /* macros common across all UARTs */
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -117,7 +117,7 @@ static const i2c_conf_t i2c_config[] = {
     },
 };
 
-#define I2C_NUMOF               (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF               ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
@@ -134,7 +134,7 @@ static const spi_conf_t spi_config[] = {
     },
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/particle-argon/include/periph_conf.h b/boards/particle-argon/include/periph_conf.h
index 98b0b2c6ca..b6dd16dd9b 100644
--- a/boards/particle-argon/include/periph_conf.h
+++ b/boards/particle-argon/include/periph_conf.h
@@ -53,7 +53,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_uart0)
 #define UART_1_ISR          (isr_uarte1)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/particle-boron/include/periph_conf.h b/boards/particle-boron/include/periph_conf.h
index 6b525daa39..56a9fd21fa 100644
--- a/boards/particle-boron/include/periph_conf.h
+++ b/boards/particle-boron/include/periph_conf.h
@@ -53,7 +53,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_uart0)
 #define UART_1_ISR          (isr_uarte1)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 #ifdef __cplusplus
 }
diff --git a/boards/particle-xenon/include/periph_conf.h b/boards/particle-xenon/include/periph_conf.h
index 029d80215a..92126b84ce 100644
--- a/boards/particle-xenon/include/periph_conf.h
+++ b/boards/particle-xenon/include/periph_conf.h
@@ -44,7 +44,7 @@ static const uart_conf_t uart_config[] = {
 
 #define UART_0_ISR          (isr_uart0)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/pba-d-01-kw2x/include/periph_conf.h b/boards/pba-d-01-kw2x/include/periph_conf.h
index c8afe2c38c..950de4a6a7 100644
--- a/boards/pba-d-01-kw2x/include/periph_conf.h
+++ b/boards/pba-d-01-kw2x/include/periph_conf.h
@@ -127,7 +127,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_uart2_rx_tx)
 #define UART_1_ISR          (isr_uart0_rx_tx)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -143,7 +143,7 @@ static const adc_conf_t adc_config[] = {
     [ 5] = { .dev = ADC0, .pin = GPIO_PIN(PORT_E, 1), .chan = 11, .avg = ADC_AVG_MAX }
 };
 
-#define ADC_NUMOF           (sizeof(adc_config) / sizeof(adc_config[0]))
+#define ADC_NUMOF           ARRAY_SIZE(adc_config)
 /*
  * KW2xD ADC reference settings:
  * 0: VREFH/VREFL external pin pair
@@ -170,7 +170,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 
@@ -250,7 +250,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 
@@ -270,7 +270,7 @@ static const i2c_conf_t i2c_config[] = {
         .sda_pcr = (PORT_PCR_MUX(6) | PORT_PCR_ODE_MASK),
     },
 };
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 #define I2C_0_ISR           (isr_i2c1)
 /** @} */
 
diff --git a/boards/phynode-kw41z/include/periph_conf.h b/boards/phynode-kw41z/include/periph_conf.h
index a334cb2241..9b4cbb037d 100644
--- a/boards/phynode-kw41z/include/periph_conf.h
+++ b/boards/phynode-kw41z/include/periph_conf.h
@@ -51,7 +51,7 @@ static const spi_conf_t spi_config[] = {
         .simmask  = SIM_SCGC6_SPI1_MASK
     }
 };
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -71,7 +71,7 @@ static const adc_conf_t adc_config[] = {
     /* internal: DCDC divided battery level */
     [ 2] = { .dev = ADC0, .pin = GPIO_UNDEF, .chan = 23, .avg = ADC_AVG_MAX },
 };
-#define ADC_NUMOF           (sizeof(adc_config) / sizeof(adc_config[0]))
+#define ADC_NUMOF           ARRAY_SIZE(adc_config)
 /*
  * KW41Z ADC reference settings:
  * 0: VREFH external pin or VREF_OUT 1.2 V signal (if VREF module is enabled)
diff --git a/boards/pyboard/include/periph_conf.h b/boards/pyboard/include/periph_conf.h
index 56741bb9b2..46aa22ce11 100644
--- a/boards/pyboard/include/periph_conf.h
+++ b/boards/pyboard/include/periph_conf.h
@@ -74,7 +74,7 @@ static const timer_conf_t timer_config[] = {
 
 #define TIMER_0_ISR         isr_tim5
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -100,7 +100,7 @@ static const uart_conf_t uart_config[] = {
 
 #define UART_0_ISR          (isr_usart1)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -146,7 +146,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -170,7 +170,7 @@ static const i2c_conf_t i2c_config[] = {
 
 #define I2C_0_ISR           isr_i2c2_er
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/reel/include/periph_conf.h b/boards/reel/include/periph_conf.h
index ed67d8dd9d..c8e4329560 100644
--- a/boards/reel/include/periph_conf.h
+++ b/boards/reel/include/periph_conf.h
@@ -47,7 +47,7 @@ static const uart_conf_t uart_config[] = {
 
 #define UART_0_ISR          (isr_uart0)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -63,7 +63,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/remote-pa/include/periph_conf.h b/boards/remote-pa/include/periph_conf.h
index ad0269b11a..26178c2400 100644
--- a/boards/remote-pa/include/periph_conf.h
+++ b/boards/remote-pa/include/periph_conf.h
@@ -42,7 +42,7 @@ static const i2c_conf_t i2c_config[] = {
     },
 };
 
-#define I2C_NUMOF               (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF               ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
@@ -66,7 +66,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -80,7 +80,7 @@ static const adc_conf_t adc_config[] = {
     GPIO_PIN(0, 7), /**< GPIO_PA7 = ADC3_PIN */
 };
 
-#define ADC_NUMOF           (sizeof(adc_config) / sizeof(adc_config[0]))
+#define ADC_NUMOF           ARRAY_SIZE(adc_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/remote-reva/include/periph_conf.h b/boards/remote-reva/include/periph_conf.h
index 4186dc9705..29e322be11 100644
--- a/boards/remote-reva/include/periph_conf.h
+++ b/boards/remote-reva/include/periph_conf.h
@@ -42,7 +42,7 @@ static const i2c_conf_t i2c_config[] = {
     },
 };
 
-#define I2C_NUMOF               (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF               ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
@@ -66,7 +66,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -82,7 +82,7 @@ static const adc_conf_t adc_config[] = {
     GPIO_PIN(0, 2), /**< GPIO_PA2 = ADC3_PIN */
 };
 
-#define ADC_NUMOF           (sizeof(adc_config) / sizeof(adc_config[0]))
+#define ADC_NUMOF           ARRAY_SIZE(adc_config)
 /** @} */
 
 
diff --git a/boards/remote-revb/include/periph_conf.h b/boards/remote-revb/include/periph_conf.h
index e6bb958b2b..340d1f8abe 100644
--- a/boards/remote-revb/include/periph_conf.h
+++ b/boards/remote-revb/include/periph_conf.h
@@ -45,7 +45,7 @@ static const i2c_conf_t i2c_config[] = {
     },
 };
 
-#define I2C_NUMOF               (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF               ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
@@ -68,7 +68,7 @@ static const spi_conf_t spi_config[] = {
         .cs_pin   = GPIO_PIN(0, 7)
     }
 };
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -84,7 +84,7 @@ static const adc_conf_t adc_config[] = {
     GPIO_PIN(0, 2), /**< GPIO_PA2 = ADC3_PIN */
 };
 
-#define ADC_NUMOF           (sizeof(adc_config) / sizeof(adc_config[0]))
+#define ADC_NUMOF           ARRAY_SIZE(adc_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/ruuvitag/include/periph_conf.h b/boards/ruuvitag/include/periph_conf.h
index eaab812e48..d63e19a10a 100644
--- a/boards/ruuvitag/include/periph_conf.h
+++ b/boards/ruuvitag/include/periph_conf.h
@@ -42,7 +42,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
diff --git a/boards/samd21-xpro/include/periph_conf.h b/boards/samd21-xpro/include/periph_conf.h
index ce3231ba4d..fc6f4181ed 100644
--- a/boards/samd21-xpro/include/periph_conf.h
+++ b/boards/samd21-xpro/include/periph_conf.h
@@ -126,7 +126,7 @@ static const tc32_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tc3
 #define TIMER_1_ISR         isr_tc4
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -171,7 +171,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          isr_sercom4
 #define UART_2_ISR          isr_sercom5
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -256,7 +256,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -274,7 +274,7 @@ static const i2c_conf_t i2c_config[] = {
         .flags    = I2C_FLAG_NONE
      }
 };
-#define I2C_NUMOF          (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF          ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
diff --git a/boards/same54-xpro/include/periph_conf.h b/boards/same54-xpro/include/periph_conf.h
index 69a6e7ed4a..35fefeda19 100644
--- a/boards/same54-xpro/include/periph_conf.h
+++ b/boards/same54-xpro/include/periph_conf.h
@@ -66,7 +66,7 @@ static const tc32_conf_t timer_config[] = {
 #define TIMER_1_CHANNELS    2
 #define TIMER_1_ISR         isr_tc2
 
-#define TIMER_NUMOF         (sizeof(timer_config)/sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -89,7 +89,7 @@ static const uart_conf_t uart_config[] = {
 /* interrupt function name mapping */
 #define UART_0_ISR          isr_sercom2_2
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -111,7 +111,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -130,7 +130,7 @@ static const i2c_conf_t i2c_config[] = {
     }
 };
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 
diff --git a/boards/saml21-xpro/include/periph_conf.h b/boards/saml21-xpro/include/periph_conf.h
index 95c4b8b2ed..0bff0f1747 100644
--- a/boards/saml21-xpro/include/periph_conf.h
+++ b/boards/saml21-xpro/include/periph_conf.h
@@ -54,7 +54,7 @@ static const tc32_conf_t timer_config[] = {
 /* Timer 0 configuration */
 #define TIMER_0_CHANNELS    2
 #define TIMER_0_ISR         isr_tc0
-#define TIMER_NUMOF         (sizeof(timer_config)/sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -88,7 +88,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          isr_sercom3
 #define UART_1_ISR          isr_sercom4
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -110,7 +110,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -129,7 +129,7 @@ static const i2c_conf_t i2c_config[] = {
     }
 };
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
diff --git a/boards/samr21-xpro/include/periph_conf.h b/boards/samr21-xpro/include/periph_conf.h
index c405144baf..1690b45e66 100644
--- a/boards/samr21-xpro/include/periph_conf.h
+++ b/boards/samr21-xpro/include/periph_conf.h
@@ -126,7 +126,7 @@ static const tc32_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tc3
 #define TIMER_1_ISR         isr_tc4
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -160,7 +160,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          isr_sercom0
 #define UART_1_ISR          isr_sercom5
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -227,7 +227,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -245,7 +245,7 @@ static const i2c_conf_t i2c_config[] = {
         .flags    = I2C_FLAG_NONE
      }
 };
-#define I2C_NUMOF          (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF          ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
diff --git a/boards/samr30-xpro/include/periph_conf.h b/boards/samr30-xpro/include/periph_conf.h
index 1ff3d224ef..fe5bcacf76 100644
--- a/boards/samr30-xpro/include/periph_conf.h
+++ b/boards/samr30-xpro/include/periph_conf.h
@@ -50,7 +50,7 @@ static const tc32_conf_t timer_config[] = {
 /* Timer 0 configuration */
 #define TIMER_0_CHANNELS    2
 #define TIMER_0_ISR         isr_tc0
-#define TIMER_NUMOF         (sizeof(timer_config)/sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -73,7 +73,7 @@ static const uart_conf_t uart_config[] = {
 /* interrupt function name mapping */
 #define UART_0_ISR          isr_sercom0
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -94,7 +94,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -112,7 +112,7 @@ static const i2c_conf_t i2c_config[] = {
         .flags    = I2C_FLAG_NONE
      }
 };
-#define I2C_NUMOF          (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF          ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
diff --git a/boards/sensebox_samd21/include/periph_conf.h b/boards/sensebox_samd21/include/periph_conf.h
index 403416a1bd..e8ea3f71fb 100644
--- a/boards/sensebox_samd21/include/periph_conf.h
+++ b/boards/sensebox_samd21/include/periph_conf.h
@@ -116,7 +116,7 @@ static const tc32_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tc3
 #define TIMER_1_ISR         isr_tc4
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -150,7 +150,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          isr_sercom3
 #define UART_1_ISR          isr_sercom4
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -171,7 +171,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 
 /**
  * @name    I2C configuration
@@ -198,7 +198,7 @@ static const i2c_conf_t i2c_config[] = {
     }
 };
 
-#define I2C_NUMOF          (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF          ARRAY_SIZE(i2c_config)
 
 /**
  * @name    RTC configuration
diff --git a/boards/slstk3401a/include/periph_conf.h b/boards/slstk3401a/include/periph_conf.h
index 80788ceb68..8345b394b3 100644
--- a/boards/slstk3401a/include/periph_conf.h
+++ b/boards/slstk3401a/include/periph_conf.h
@@ -28,11 +28,6 @@
 extern "C" {
 #endif
 
-/**
- * @brief   Internal macro to calculate *_NUMOF based on config.
- */
-#define PERIPH_NUMOF(config)    (sizeof(config) / sizeof(config[0]))
-
 /**
  * @name    Clock configuration
  * @{
@@ -89,8 +84,8 @@ static const adc_chan_conf_t adc_channel_config[] = {
     }
 };
 
-#define ADC_DEV_NUMOF       PERIPH_NUMOF(adc_config)
-#define ADC_NUMOF           PERIPH_NUMOF(adc_channel_config)
+#define ADC_DEV_NUMOF       ARRAY_SIZE(adc_config)
+#define ADC_NUMOF           ARRAY_SIZE(adc_channel_config)
 /** @} */
 
 /**
@@ -110,7 +105,7 @@ static const i2c_conf_t i2c_config[] = {
     }
 };
 
-#define I2C_NUMOF           PERIPH_NUMOF(i2c_config)
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 #define I2C_0_ISR           isr_i2c0
 /** @} */
 
@@ -147,7 +142,7 @@ static const spi_dev_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           PERIPH_NUMOF(spi_config)
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -170,7 +165,7 @@ static const timer_conf_t timer_config[] = {
     }
 };
 
-#define TIMER_NUMOF         PERIPH_NUMOF(timer_config)
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 #define TIMER_0_ISR         isr_timer1
 /** @} */
 
@@ -217,7 +212,7 @@ static const uart_conf_t uart_config[] = {
     }
 };
 
-#define UART_NUMOF          PERIPH_NUMOF(uart_config)
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 #define UART_0_ISR_RX       isr_usart0_rx
 #define UART_1_ISR_RX       isr_usart1_rx
 #define UART_2_ISR_RX       isr_leuart0
diff --git a/boards/slstk3402a/include/periph_conf.h b/boards/slstk3402a/include/periph_conf.h
index 4c0f40e042..8fbea50d64 100644
--- a/boards/slstk3402a/include/periph_conf.h
+++ b/boards/slstk3402a/include/periph_conf.h
@@ -28,11 +28,6 @@
 extern "C" {
 #endif
 
-/**
- * @brief   Internal macro to calculate *_NUMOF based on config.
- */
-#define PERIPH_NUMOF(config)    (sizeof(config) / sizeof(config[0]))
-
 /**
  * @name    Clock configuration
  * @{
@@ -80,8 +75,8 @@ static const adc_chan_conf_t adc_channel_config[] = {
     }
 };
 
-#define ADC_DEV_NUMOF       PERIPH_NUMOF(adc_config)
-#define ADC_NUMOF           PERIPH_NUMOF(adc_channel_config)
+#define ADC_DEV_NUMOF       ARRAY_SIZE(adc_config)
+#define ADC_NUMOF           ARRAY_SIZE(adc_channel_config)
 /** @} */
 
 /**
@@ -101,7 +96,7 @@ static const i2c_conf_t i2c_config[] = {
     }
 };
 
-#define I2C_NUMOF           PERIPH_NUMOF(i2c_config)
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 #define I2C_0_ISR           isr_i2c0
 /** @} */
 
@@ -138,7 +133,7 @@ static const spi_dev_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           PERIPH_NUMOF(spi_config)
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -161,7 +156,7 @@ static const timer_conf_t timer_config[] = {
     }
 };
 
-#define TIMER_NUMOF         PERIPH_NUMOF(timer_config)
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 #define TIMER_0_ISR         isr_wtimer1
 /** @} */
 
@@ -196,7 +191,7 @@ static const uart_conf_t uart_config[] = {
     }
 };
 
-#define UART_NUMOF          PERIPH_NUMOF(uart_config)
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 #define UART_0_ISR_RX       isr_usart0_rx
 #define UART_1_ISR_RX       isr_leuart0
 /** @} */
diff --git a/boards/sltb001a/include/periph_conf.h b/boards/sltb001a/include/periph_conf.h
index b4f6b4b4c7..a41053bd13 100644
--- a/boards/sltb001a/include/periph_conf.h
+++ b/boards/sltb001a/include/periph_conf.h
@@ -28,11 +28,6 @@
 extern "C" {
 #endif
 
-/**
- * @brief   Internal macro to calculate *_NUMOF based on config.
- */
-#define PERIPH_NUMOF(config)    (sizeof(config) / sizeof(config[0]))
-
 /**
  * @name    Clock configuration
  * @{
@@ -89,8 +84,8 @@ static const adc_chan_conf_t adc_channel_config[] = {
     }
 };
 
-#define ADC_DEV_NUMOF       PERIPH_NUMOF(adc_config)
-#define ADC_NUMOF           PERIPH_NUMOF(adc_channel_config)
+#define ADC_DEV_NUMOF       ARRAY_SIZE(adc_config)
+#define ADC_NUMOF           ARRAY_SIZE(adc_channel_config)
 /** @} */
 
 /**
@@ -110,7 +105,7 @@ static const i2c_conf_t i2c_config[] = {
     }
 };
 
-#define I2C_NUMOF           PERIPH_NUMOF(i2c_config)
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 #define I2C_0_ISR           isr_i2c0
 /** @} */
 
@@ -147,7 +142,7 @@ static const spi_dev_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           PERIPH_NUMOF(spi_config)
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -170,7 +165,7 @@ static const timer_conf_t timer_config[] = {
     }
 };
 
-#define TIMER_NUMOF         PERIPH_NUMOF(timer_config)
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 #define TIMER_0_ISR         isr_timer1
 /** @} */
 
@@ -217,7 +212,7 @@ static const uart_conf_t uart_config[] = {
     }
 };
 
-#define UART_NUMOF          PERIPH_NUMOF(uart_config)
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 #define UART_0_ISR_RX       isr_usart0_rx
 #define UART_1_ISR_RX       isr_usart1_rx
 #define UART_2_ISR_RX       isr_leuart0
diff --git a/boards/slwstk6000b/include/periph_conf.h b/boards/slwstk6000b/include/periph_conf.h
index 675fa085be..2e680a30a4 100644
--- a/boards/slwstk6000b/include/periph_conf.h
+++ b/boards/slwstk6000b/include/periph_conf.h
@@ -30,11 +30,6 @@
 extern "C" {
 #endif
 
-/**
- * @brief   Internal macro to calculate *_NUMOF based on config.
- */
-#define PERIPH_NUMOF(config)    (sizeof(config) / sizeof(config[0]))
-
 /**
  * @name    Clock configuration
  * @{
@@ -82,8 +77,8 @@ static const adc_chan_conf_t adc_channel_config[] = {
     }
 };
 
-#define ADC_DEV_NUMOF       PERIPH_NUMOF(adc_config)
-#define ADC_NUMOF           PERIPH_NUMOF(adc_channel_config)
+#define ADC_DEV_NUMOF       ARRAY_SIZE(adc_config)
+#define ADC_NUMOF           ARRAY_SIZE(adc_channel_config)
 /** @} */
 
 /**
@@ -103,7 +98,7 @@ static const i2c_conf_t i2c_config[] = {
     }
 };
 
-#define I2C_NUMOF           PERIPH_NUMOF(i2c_config)
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 #define I2C_0_ISR           isr_i2c0
 /** @} */
 
@@ -140,7 +135,7 @@ static const spi_dev_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           PERIPH_NUMOF(spi_config)
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -163,7 +158,7 @@ static const timer_conf_t timer_config[] = {
     }
 };
 
-#define TIMER_NUMOF         PERIPH_NUMOF(timer_config)
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 #define TIMER_0_ISR         isr_timer1
 /** @} */
 
@@ -186,7 +181,7 @@ static const uart_conf_t uart_config[] = {
     }
 };
 
-#define UART_NUMOF          PERIPH_NUMOF(uart_config)
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 #define UART_0_ISR_RX       isr_usart0_rx
 /** @} */
 
diff --git a/boards/slwstk6220a/include/periph_conf.h b/boards/slwstk6220a/include/periph_conf.h
index eb591069a9..fcdd271400 100644
--- a/boards/slwstk6220a/include/periph_conf.h
+++ b/boards/slwstk6220a/include/periph_conf.h
@@ -63,7 +63,7 @@ static const timer_conf_t timer_config[] = {
 
 #define TIMER_0_ISR         isr_timer1
 #define TIMER_0_MAX_VALUE   (0xffff)            /* 16-bit timer */
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -82,7 +82,7 @@ static const uart_conf_t uart_config[] = {
 };
 
 #define UART_0_ISR_RX       isr_usart2_rx
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/sodaq-autonomo/include/periph_conf.h b/boards/sodaq-autonomo/include/periph_conf.h
index 0b6560f402..12bea36f82 100644
--- a/boards/sodaq-autonomo/include/periph_conf.h
+++ b/boards/sodaq-autonomo/include/periph_conf.h
@@ -116,7 +116,7 @@ static const tc32_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tc3
 #define TIMER_1_ISR         isr_tc4
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -173,7 +173,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_2_ISR          isr_sercom4
 #define UART_3_ISR          isr_sercom1
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -229,7 +229,7 @@ static const spi_conf_t spi_config[] = {
     },
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -247,7 +247,7 @@ static const i2c_conf_t i2c_config[] = {
         .flags    = I2C_FLAG_NONE
      }
 };
-#define I2C_NUMOF          (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF          ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
diff --git a/boards/sodaq-explorer/include/periph_conf.h b/boards/sodaq-explorer/include/periph_conf.h
index 0a86a7b747..4976036ded 100644
--- a/boards/sodaq-explorer/include/periph_conf.h
+++ b/boards/sodaq-explorer/include/periph_conf.h
@@ -113,7 +113,7 @@ static const tc32_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tc3
 #define TIMER_1_ISR         isr_tc4
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -158,7 +158,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          isr_sercom4
 #define UART_2_ISR          isr_sercom0
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -212,7 +212,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -239,7 +239,7 @@ static const i2c_conf_t i2c_config[] = {
         .flags    = I2C_FLAG_NONE
     }
 };
-#define I2C_NUMOF          (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF          ARRAY_SIZE(i2c_config)
 
 /** @} */
 
diff --git a/boards/sodaq-one/include/periph_conf.h b/boards/sodaq-one/include/periph_conf.h
index a1b9d5c6cb..d1cbc2f8ac 100644
--- a/boards/sodaq-one/include/periph_conf.h
+++ b/boards/sodaq-one/include/periph_conf.h
@@ -116,7 +116,7 @@ static const tc32_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tc3
 #define TIMER_1_ISR         isr_tc4
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -151,7 +151,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          isr_sercom5
 #define UART_1_ISR          isr_sercom2
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -214,7 +214,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -232,7 +232,7 @@ static const i2c_conf_t i2c_config[] = {
         .flags    = I2C_FLAG_NONE
     }
 };
-#define I2C_NUMOF          (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF          ARRAY_SIZE(i2c_config)
 
 /** @} */
 
diff --git a/boards/sodaq-sara-aff/include/periph_conf.h b/boards/sodaq-sara-aff/include/periph_conf.h
index 90dbde2b33..be0396c038 100644
--- a/boards/sodaq-sara-aff/include/periph_conf.h
+++ b/boards/sodaq-sara-aff/include/periph_conf.h
@@ -118,7 +118,7 @@ static const tc32_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tc3
 #define TIMER_1_ISR         isr_tc4
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -153,7 +153,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          isr_sercom5
 #define UART_1_ISR          isr_sercom0
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -211,7 +211,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -229,7 +229,7 @@ static const i2c_conf_t i2c_config[] = {
         .flags    = I2C_FLAG_NONE
     }
 };
-#define I2C_NUMOF          (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF          ARRAY_SIZE(i2c_config)
 
 /** @} */
 
diff --git a/boards/spark-core/include/periph_conf.h b/boards/spark-core/include/periph_conf.h
index 88abec5535..572b1daa08 100644
--- a/boards/spark-core/include/periph_conf.h
+++ b/boards/spark-core/include/periph_conf.h
@@ -83,7 +83,7 @@ static const timer_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tim2
 #define TIMER_1_ISR         isr_tim3
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -103,7 +103,7 @@ static const uart_conf_t uart_config[] = {
 
 #define UART_0_ISR          (isr_usart2)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -142,7 +142,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/stk3600/include/periph_conf.h b/boards/stk3600/include/periph_conf.h
index 29fcbe12b5..51d4681952 100644
--- a/boards/stk3600/include/periph_conf.h
+++ b/boards/stk3600/include/periph_conf.h
@@ -28,11 +28,6 @@
 extern "C" {
 #endif
 
-/**
- * @brief   Internal macro to calculate *_NUMOF based on config.
- */
-#define PERIPH_NUMOF(config)    (sizeof(config) / sizeof(config[0]))
-
 /**
  * @name    Clock configuration
  * @{
@@ -77,8 +72,8 @@ static const adc_chan_conf_t adc_channel_config[] = {
     }
 };
 
-#define ADC_DEV_NUMOF       PERIPH_NUMOF(adc_config)
-#define ADC_NUMOF           PERIPH_NUMOF(adc_channel_config)
+#define ADC_DEV_NUMOF       ARRAY_SIZE(adc_config)
+#define ADC_NUMOF           ARRAY_SIZE(adc_channel_config)
 /** @} */
 
 /**
@@ -100,8 +95,8 @@ static const dac_chan_conf_t dac_channel_config[] = {
     }
 };
 
-#define DAC_DEV_NUMOF       PERIPH_NUMOF(dac_config)
-#define DAC_NUMOF           PERIPH_NUMOF(dac_channel_config)
+#define DAC_DEV_NUMOF       ARRAY_SIZE(dac_config)
+#define DAC_NUMOF           ARRAY_SIZE(dac_channel_config)
 /** @} */
 
 /**
@@ -129,7 +124,7 @@ static const i2c_conf_t i2c_config[] = {
     }
 };
 
-#define I2C_NUMOF           PERIPH_NUMOF(i2c_config)
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 #define I2C_0_ISR           isr_i2c0
 #define I2C_1_ISR           isr_i2c1
 /** @} */
@@ -156,8 +151,8 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_DEV_NUMOF       PERIPH_NUMOF(pwm_config)
-#define PWM_NUMOF           PERIPH_NUMOF(pwm_channel_config)
+#define PWM_DEV_NUMOF       ARRAY_SIZE(pwm_config)
+#define PWM_NUMOF           ARRAY_SIZE(pwm_channel_config)
 /** @} */
 
 /**
@@ -202,7 +197,7 @@ static const spi_dev_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           PERIPH_NUMOF(spi_config)
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -225,7 +220,7 @@ static const timer_conf_t timer_config[] = {
     }
 };
 
-#define TIMER_NUMOF         PERIPH_NUMOF(timer_config)
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 #define TIMER_0_ISR         isr_timer1
 /** @} */
 
@@ -269,7 +264,7 @@ static const uart_conf_t uart_config[] = {
     }
 };
 
-#define UART_NUMOF          PERIPH_NUMOF(uart_config)
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 #define UART_0_ISR_RX       isr_uart0_rx
 #define UART_1_ISR_RX       isr_usart1_rx
 #define UART_2_ISR_RX       isr_leuart0
diff --git a/boards/stk3700/include/periph_conf.h b/boards/stk3700/include/periph_conf.h
index e855fb742a..c1212e0659 100644
--- a/boards/stk3700/include/periph_conf.h
+++ b/boards/stk3700/include/periph_conf.h
@@ -28,11 +28,6 @@
 extern "C" {
 #endif
 
-/**
- * @brief   Internal macro to calculate *_NUMOF based on config.
- */
-#define PERIPH_NUMOF(config)    (sizeof(config) / sizeof(config[0]))
-
 /**
  * @name    Clock configuration
  * @{
@@ -77,8 +72,8 @@ static const adc_chan_conf_t adc_channel_config[] = {
     }
 };
 
-#define ADC_DEV_NUMOF       PERIPH_NUMOF(adc_config)
-#define ADC_NUMOF           PERIPH_NUMOF(adc_channel_config)
+#define ADC_DEV_NUMOF       ARRAY_SIZE(adc_config)
+#define ADC_NUMOF           ARRAY_SIZE(adc_channel_config)
 /** @} */
 
 /**
@@ -100,8 +95,8 @@ static const dac_chan_conf_t dac_channel_config[] = {
     }
 };
 
-#define DAC_DEV_NUMOF       PERIPH_NUMOF(dac_config)
-#define DAC_NUMOF           PERIPH_NUMOF(dac_channel_config)
+#define DAC_DEV_NUMOF       ARRAY_SIZE(dac_config)
+#define DAC_NUMOF           ARRAY_SIZE(dac_channel_config)
 /** @} */
 
 /**
@@ -129,7 +124,7 @@ static const i2c_conf_t i2c_config[] = {
     }
 };
 
-#define I2C_NUMOF           PERIPH_NUMOF(i2c_config)
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 #define I2C_0_ISR           isr_i2c0
 #define I2C_1_ISR           isr_i2c1
 /** @} */
@@ -156,8 +151,8 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_DEV_NUMOF       PERIPH_NUMOF(pwm_config)
-#define PWM_NUMOF           PERIPH_NUMOF(pwm_channel_config)
+#define PWM_DEV_NUMOF       ARRAY_SIZE(pwm_config)
+#define PWM_NUMOF           ARRAY_SIZE(pwm_channel_config)
 /** @} */
 
 /**
@@ -202,7 +197,7 @@ static const spi_dev_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           PERIPH_NUMOF(spi_config)
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -225,7 +220,7 @@ static const timer_conf_t timer_config[] = {
     }
 };
 
-#define TIMER_NUMOF         PERIPH_NUMOF(timer_config)
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 #define TIMER_0_ISR         isr_timer1
 /** @} */
 
@@ -269,7 +264,7 @@ static const uart_conf_t uart_config[] = {
     }
 };
 
-#define UART_NUMOF          PERIPH_NUMOF(uart_config)
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 #define UART_0_ISR_RX       isr_uart0_rx
 #define UART_1_ISR_RX       isr_usart1_rx
 #define UART_2_ISR_RX       isr_leuart0
diff --git a/boards/stm32f0discovery/include/periph_conf.h b/boards/stm32f0discovery/include/periph_conf.h
index d382678891..f2525adf51 100644
--- a/boards/stm32f0discovery/include/periph_conf.h
+++ b/boards/stm32f0discovery/include/periph_conf.h
@@ -69,7 +69,7 @@ static const timer_conf_t timer_config[] = {
 
 #define TIMER_0_ISR         isr_tim2
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -102,7 +102,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_usart1)
 #define UART_1_ISR          (isr_usart2)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -168,7 +168,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/stm32f3discovery/include/periph_conf.h b/boards/stm32f3discovery/include/periph_conf.h
index bf7105bac9..8b9afc56ed 100644
--- a/boards/stm32f3discovery/include/periph_conf.h
+++ b/boards/stm32f3discovery/include/periph_conf.h
@@ -62,7 +62,7 @@ static const dac_conf_t dac_config[] = {
     { .pin = GPIO_PIN(PORT_A,  4), .chan = 0 }
 };
 
-#define DAC_NUMOF           (sizeof(dac_config) / sizeof(dac_config[0]))
+#define DAC_NUMOF           ARRAY_SIZE(dac_config)
 /** @} */
 
 /**
@@ -81,7 +81,7 @@ static const timer_conf_t timer_config[] = {
 
 #define TIMER_0_ISR         isr_tim2
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -125,7 +125,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          (isr_usart2)
 #define UART_2_ISR          (isr_usart3)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -155,7 +155,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -202,7 +202,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -239,7 +239,7 @@ static const i2c_conf_t i2c_config[] = {
 #define I2C_0_ISR           isr_i2c1_er
 #define I2C_1_ISR           isr_i2c2_er
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/stm32f429i-disc1/include/periph_conf.h b/boards/stm32f429i-disc1/include/periph_conf.h
index 8301d04447..b3c2f26389 100644
--- a/boards/stm32f429i-disc1/include/periph_conf.h
+++ b/boards/stm32f429i-disc1/include/periph_conf.h
@@ -52,7 +52,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_usart1)
 #define UART_0_DMA_ISR      (isr_dma1_stream6)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -75,7 +75,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -99,7 +99,7 @@ static const i2c_conf_t i2c_config[] = {
 
 #define I2C_0_ISR           isr_i2c3_ev
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/stm32f4discovery/include/periph_conf.h b/boards/stm32f4discovery/include/periph_conf.h
index e209748d01..ba5fff2e56 100644
--- a/boards/stm32f4discovery/include/periph_conf.h
+++ b/boards/stm32f4discovery/include/periph_conf.h
@@ -52,7 +52,7 @@ static const timer_conf_t timer_config[] = {
 #define TIMER_0_ISR         isr_tim2
 #define TIMER_1_ISR         isr_tim5
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -95,7 +95,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_1_ISR          (isr_usart3)
 #define UART_1_DMA_ISR      (isr_dma1_stream3)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -124,7 +124,7 @@ static const dac_conf_t dac_config[] = {
     { .pin = GPIO_PIN(PORT_A,  5), .chan = 1 }
 };
 
-#define DAC_NUMOF           (sizeof(dac_config) / sizeof(dac_config[0]))
+#define DAC_NUMOF           ARRAY_SIZE(dac_config)
 /** @} */
 
 /**
@@ -154,7 +154,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 /**
@@ -184,7 +184,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -208,7 +208,7 @@ static const i2c_conf_t i2c_config[] = {
 
 #define I2C_0_ISR           isr_i2c1_ev
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/stm32f769i-disco/include/periph_conf.h b/boards/stm32f769i-disco/include/periph_conf.h
index 9c55d11997..dda83fac6c 100644
--- a/boards/stm32f769i-disco/include/periph_conf.h
+++ b/boards/stm32f769i-disco/include/periph_conf.h
@@ -82,7 +82,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_usart1)
 #define UART_0_DMA_ISR      (isr_dma1_stream4)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/stm32l0538-disco/include/periph_conf.h b/boards/stm32l0538-disco/include/periph_conf.h
index 3d314613d5..4a730b84d0 100644
--- a/boards/stm32l0538-disco/include/periph_conf.h
+++ b/boards/stm32l0538-disco/include/periph_conf.h
@@ -66,7 +66,7 @@ static const timer_conf_t timer_config[] = {
 
 #define TIMER_0_ISR         isr_tim2
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -90,7 +90,7 @@ static const uart_conf_t uart_config[] = {
 
 #define UART_0_ISR          (isr_usart1)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -140,7 +140,7 @@ static const spi_conf_t spi_config[] = {
     },
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/stm32l476g-disco/include/periph_conf.h b/boards/stm32l476g-disco/include/periph_conf.h
index 98c20f7606..1eb5ed1f5d 100644
--- a/boards/stm32l476g-disco/include/periph_conf.h
+++ b/boards/stm32l476g-disco/include/periph_conf.h
@@ -86,7 +86,7 @@ static const timer_conf_t timer_config[] = {
 
 #define TIMER_0_ISR         isr_tim5
 
-#define TIMER_NUMOF         (sizeof(timer_config) / sizeof(timer_config[0]))
+#define TIMER_NUMOF         ARRAY_SIZE(timer_config)
 /** @} */
 
 /**
@@ -114,7 +114,7 @@ static const uart_conf_t uart_config[] = {
 
 #define UART_0_ISR          (isr_usart2)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/teensy31/include/periph_conf.h b/boards/teensy31/include/periph_conf.h
index c9024e04dd..67c55d7fc1 100644
--- a/boards/teensy31/include/periph_conf.h
+++ b/boards/teensy31/include/periph_conf.h
@@ -132,7 +132,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_0_ISR          (isr_uart0_rx_tx)
 #define UART_1_ISR          (isr_uart1_rx_tx)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -164,7 +164,7 @@ static const pwm_conf_t pwm_config[] = {
     }
 };
 
-#define PWM_NUMOF           (sizeof(pwm_config) / sizeof(pwm_config[0]))
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
 /** @} */
 
 #ifdef __cplusplus
diff --git a/boards/ublox-c030-u201/include/periph_conf.h b/boards/ublox-c030-u201/include/periph_conf.h
index 1e94b578cc..8604274737 100644
--- a/boards/ublox-c030-u201/include/periph_conf.h
+++ b/boards/ublox-c030-u201/include/periph_conf.h
@@ -133,7 +133,7 @@ static const uart_conf_t uart_config[] = {
 #define UART_2_ISR          (isr_usart6)
 #define UART_3_ISR          (isr_usart3)
 
-#define UART_NUMOF          (sizeof(uart_config) / sizeof(uart_config[0]))
+#define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
 /**
@@ -173,7 +173,7 @@ static const spi_conf_t spi_config[] = {
     },
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -210,7 +210,7 @@ static const i2c_conf_t i2c_config[] = {
 #define I2C_0_ISR           isr_i2c1_ev
 #define I2C_1_ISR           isr_i2c3_ev
 
-#define I2C_NUMOF (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
diff --git a/boards/usb-kw41z/include/periph_conf.h b/boards/usb-kw41z/include/periph_conf.h
index 025fd5c56f..c607b38394 100644
--- a/boards/usb-kw41z/include/periph_conf.h
+++ b/boards/usb-kw41z/include/periph_conf.h
@@ -48,7 +48,7 @@ static const spi_conf_t spi_config[] = {
         .simmask  = SIM_SCGC6_SPI1_MASK
     }
 };
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -68,7 +68,7 @@ static const adc_conf_t adc_config[] = {
     /* internal: DCDC divided battery level */
     [ 2] = { .dev = ADC0, .pin = GPIO_UNDEF, .chan = 23, .avg = ADC_AVG_MAX },
 };
-#define ADC_NUMOF           (sizeof(adc_config) / sizeof(adc_config[0]))
+#define ADC_NUMOF           ARRAY_SIZE(adc_config)
 /*
  * KW41Z ADC reference settings:
  * 0: VREFH external pin or VREF_OUT 1.2 V signal (if VREF module is enabled)
diff --git a/boards/yunjia-nrf51822/include/periph_conf.h b/boards/yunjia-nrf51822/include/periph_conf.h
index df98c44f34..affd910217 100644
--- a/boards/yunjia-nrf51822/include/periph_conf.h
+++ b/boards/yunjia-nrf51822/include/periph_conf.h
@@ -57,7 +57,7 @@ static const spi_conf_t spi_config[] = {
     }
 };
 
-#define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
+#define SPI_NUMOF           ARRAY_SIZE(spi_config)
 /** @} */
 
 /**
@@ -74,7 +74,7 @@ static const i2c_conf_t i2c_config[] = {
     }
 };
 
-#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+#define I2C_NUMOF           ARRAY_SIZE(i2c_config)
 /** @} */
 
 /**
diff --git a/cpu/mips_pic32_common/periph/gpio.c b/cpu/mips_pic32_common/periph/gpio.c
index 090c3e745c..21d5bb226d 100644
--- a/cpu/mips_pic32_common/periph/gpio.c
+++ b/cpu/mips_pic32_common/periph/gpio.c
@@ -116,7 +116,7 @@ static PIC32_GPIO_T base_address[] = {
 
 static inline int check_valid_port(uint8_t port)
 {
-    return port < (sizeof(base_address)/sizeof(base_address[0]))
+    return port < ARRAY_SIZE(base_address)
         && base_address[port].gpio != NULL;
 }