diff --git a/cpu/samd21/periph/i2c.c b/cpu/samd21/periph/i2c.c
index f4615bc128..1c334c468f 100644
--- a/cpu/samd21/periph/i2c.c
+++ b/cpu/samd21/periph/i2c.c
@@ -204,12 +204,6 @@ int i2c_init_master(i2c_t dev, i2c_speed_t speed)
     return 0;
 }
 
-int i2c_init_slave(i2c_t dev, uint8_t address)
-{
-    /* TODO */
-    return 0;
-}
-
 int i2c_acquire(i2c_t dev)
 {
     if (dev >= I2C_NUMOF) {
diff --git a/cpu/stm32f1/periph/i2c.c b/cpu/stm32f1/periph/i2c.c
index b5d67ed024..3afac128c6 100644
--- a/cpu/stm32f1/periph/i2c.c
+++ b/cpu/stm32f1/periph/i2c.c
@@ -152,12 +152,6 @@ static void _pin_config(gpio_t scl, gpio_t sda)
     gpio_init_af(sda, GPIO_AF_OUT_OD);
 }
 
-int i2c_init_slave(i2c_t dev, uint8_t address)
-{
-    /* TODO: implement slave mode */
-    return -1;
-}
-
 int i2c_acquire(i2c_t dev)
 {
     if (dev >= I2C_NUMOF) {
diff --git a/cpu/stm32f3/periph/i2c.c b/cpu/stm32f3/periph/i2c.c
index 0aecde79a5..1fa9c57d85 100644
--- a/cpu/stm32f3/periph/i2c.c
+++ b/cpu/stm32f3/periph/i2c.c
@@ -227,12 +227,6 @@ static void _pin_config(GPIO_TypeDef *port_scl, GPIO_TypeDef *port_sda,
     }
 }
 
-int i2c_init_slave(i2c_t dev, uint8_t address)
-{
-    /* TODO: implement slave mode */
-    return -1;
-}
-
 int i2c_acquire(i2c_t dev)
 {
     if (dev >= I2C_NUMOF) {
diff --git a/cpu/stm32f4/periph/i2c.c b/cpu/stm32f4/periph/i2c.c
index c9b9c7bc88..961572305c 100644
--- a/cpu/stm32f4/periph/i2c.c
+++ b/cpu/stm32f4/periph/i2c.c
@@ -215,14 +215,6 @@ static void _toggle_pins(GPIO_TypeDef *port_scl, GPIO_TypeDef *port_sda, int pin
     port_sda->ODR |= (1 << pin_sda);
 }
 
-int i2c_init_slave(i2c_t dev, uint8_t address)
-{
-    /* TODO: implement slave mode */
-    (void) dev;
-    (void) address;
-    return -1;
-}
-
 int i2c_acquire(i2c_t dev)
 {
     if (dev >= I2C_NUMOF) {
diff --git a/cpu/stm32l1/periph/i2c.c b/cpu/stm32l1/periph/i2c.c
index b5a08bbfb7..a3afd4e0c1 100644
--- a/cpu/stm32l1/periph/i2c.c
+++ b/cpu/stm32l1/periph/i2c.c
@@ -213,12 +213,6 @@ static void _toggle_pins(GPIO_TypeDef *port, int pin_scl, int pin_sda)
     port->ODR |= (1 << pin_sda);
 }
 
-int i2c_init_slave(i2c_t dev, uint8_t address)
-{
-    /* TODO: implement slave mode */
-    return -1;
-}
-
 int i2c_acquire(i2c_t dev)
 {
     if (dev >= I2C_NUMOF) {