diff --git a/targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F412xG/system_clock.c b/targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F412xG/system_clock.c
index 03a0abd10d..6d75fda249 100644
--- a/targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F412xG/system_clock.c
+++ b/targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F412xG/system_clock.c
@@ -167,7 +167,7 @@ MBED_WEAK uint8_t SetSysClock_PLL_HSE(uint8_t bypass)
 /******************************************************************************/
 /*            PLL (clocked by HSI) used as System clock source                */
 /******************************************************************************/
-MBED_WEAK uint8_t SetSysClock_PLL_HSI(void)
+uint8_t SetSysClock_PLL_HSI(void)
 {
     RCC_OscInitTypeDef RCC_OscInitStruct;
     RCC_ClkInitTypeDef RCC_ClkInitStruct;