diff --git a/targets/TARGET_STM/TARGET_STM32L4/device/stm32l4xx_hal_rtc_ex.c b/targets/TARGET_STM/TARGET_STM32L4/device/stm32l4xx_hal_rtc_ex.c
index 1a1b67c8d06..b543ee91ff9 100644
--- a/targets/TARGET_STM/TARGET_STM32L4/device/stm32l4xx_hal_rtc_ex.c
+++ b/targets/TARGET_STM/TARGET_STM32L4/device/stm32l4xx_hal_rtc_ex.c
@@ -1123,9 +1123,12 @@ HAL_StatusTypeDef HAL_RTCEx_SetWakeUpTimer_IT(RTC_HandleTypeDef *hrtc, uint32_t
       }
     }
   }
-
+  /* Disable the Wake-Up timer */
   __HAL_RTC_WAKEUPTIMER_DISABLE(hrtc);
 
+  /* Clear flag Wake-Up */
+  __HAL_RTC_WAKEUPTIMER_CLEAR_FLAG(hrtc, RTC_FLAG_WUTF);
+
   tickstart = HAL_GetTick();
 
   /* Wait till RTC WUTWF flag is set and if Time out is reached exit */