diff --git a/cpu/esp32/startup.c b/cpu/esp32/startup.c
index 432387e26c..11d5421b86 100644
--- a/cpu/esp32/startup.c
+++ b/cpu/esp32/startup.c
@@ -24,6 +24,7 @@
 #include <string.h>
 #include <sys/reent.h>
 
+#include "macros/units.h"
 #include "board.h"
 #include "esp_attr.h"
 #include "exceptions.h"
@@ -69,7 +70,6 @@
 #define ENABLE_DEBUG 0
 #include "debug.h"
 
-#define MHZ 1000000UL
 #define STRINGIFY(s) STRINGIFY2(s)
 #define STRINGIFY2(s) #s
 
@@ -167,7 +167,7 @@ NORETURN void IRAM call_start_cpu0 (void)
 
     LOG_STARTUP("Current clocks in Hz: CPU=%d APB=%d XTAL=%d SLOW=%d\n",
                 rtc_clk_cpu_freq_value(rtc_clk_cpu_freq_get()),
-                rtc_clk_apb_freq_get(), rtc_clk_xtal_freq_get()*MHZ,
+                rtc_clk_apb_freq_get(), MHZ(rtc_clk_xtal_freq_get()),
                 rtc_clk_slow_freq_get_hz());
 
     if (IS_ACTIVE(ENABLE_DEBUG)) {
@@ -256,7 +256,7 @@ static void IRAM system_clk_init (void)
                                                set to 2 MHz and handled later */
     }
 
-    uint32_t freq_before = rtc_clk_cpu_freq_value(rtc_clk_cpu_freq_get()) / MHZ;
+    uint32_t freq_before = rtc_clk_cpu_freq_value(rtc_clk_cpu_freq_get()) / MHZ(1);
 
     if (freq_before != CONFIG_ESP32_DEFAULT_CPU_FREQ_MHZ) {
         /* set configured CPU frequency */
@@ -324,7 +324,7 @@ static NORETURN void IRAM system_init (void)
     /* print some infos */
     LOG_STARTUP("Used clocks in Hz: CPU=%d APB=%d XTAL=%d FAST=%d SLOW=%d\n",
                 rtc_clk_cpu_freq_value(rtc_clk_cpu_freq_get()),
-                rtc_clk_apb_freq_get(), rtc_clk_xtal_freq_get()*MHZ,
+                rtc_clk_apb_freq_get(), MHZ(rtc_clk_xtal_freq_get()),
                 RTC_FAST_FREQ_8M_MHZ, rtc_clk_slow_freq_get_hz());
     LOG_STARTUP("XTAL calibration value: %d\n", esp_clk_slowclk_cal_get());
     LOG_STARTUP("Heap free: %u bytes\n", get_free_heap_size());
diff --git a/cpu/esp32/syscalls.c b/cpu/esp32/syscalls.c
index b2f773d9fa..d6fea14aed 100644
--- a/cpu/esp32/syscalls.c
+++ b/cpu/esp32/syscalls.c
@@ -27,6 +27,7 @@
 #include "syscalls.h"
 #include "timex.h"
 
+#include "macros/units.h"
 #include "rom/ets_sys.h"
 #include "rom/libc_stubs.h"
 #include "soc/rtc.h"
@@ -43,8 +44,6 @@
 #define ENABLE_DEBUG 0
 #include "debug.h"
 
-#define MHZ 1000000UL
-
 #ifdef MODULE_ESP_IDF_HEAP
 
 /* if module esp_idf_heap is used, this function has to be defined for ESP32 */
@@ -164,7 +163,7 @@ static struct syscall_stub_table s_stub_table =
 void IRAM syscalls_init_arch(void)
 {
     /* enable the system timer in us (TMG0 is enabled by default) */
-    TIMER_SYSTEM.config.divider = rtc_clk_apb_freq_get()/MHZ;
+    TIMER_SYSTEM.config.divider = rtc_clk_apb_freq_get() / MHZ(1);
     TIMER_SYSTEM.config.autoreload = 0;
     TIMER_SYSTEM.config.enable = 1;