diff --git a/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_STM32L4/stm32l4xx_hal_rcc.h b/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_STM32L4/stm32l4xx_hal_rcc.h
index 5409a64c8f..27f03456b6 100644
--- a/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_STM32L4/stm32l4xx_hal_rcc.h
+++ b/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_STM32L4/stm32l4xx_hal_rcc.h
@@ -159,7 +159,7 @@ typedef struct
   * @{
   */
 #define RCC_DBP_TIMEOUT_VALUE          ((uint32_t)100)
-#define RCC_LSE_TIMEOUT_VALUE          ((uint32_t)100)
+#define RCC_LSE_TIMEOUT_VALUE          ((uint32_t)5000)
 /**
   * @}
   */
diff --git a/libraries/mbed/targets/hal/TARGET_STM/TARGET_STM32L4/TARGET_DISCO_L476VG/device.h b/libraries/mbed/targets/hal/TARGET_STM/TARGET_STM32L4/TARGET_DISCO_L476VG/device.h
index f842633cf8..8b1f3d7ca2 100644
--- a/libraries/mbed/targets/hal/TARGET_STM/TARGET_STM32L4/TARGET_DISCO_L476VG/device.h
+++ b/libraries/mbed/targets/hal/TARGET_STM/TARGET_STM32L4/TARGET_DISCO_L476VG/device.h
@@ -48,6 +48,7 @@
 #define DEVICE_SPISLAVE         1
 
 #define DEVICE_RTC              1
+#define DEVICE_RTC_LSI          0
 
 #define DEVICE_PWMOUT           1
 
diff --git a/libraries/mbed/targets/hal/TARGET_STM/TARGET_STM32L4/rtc_api.c b/libraries/mbed/targets/hal/TARGET_STM/TARGET_STM32L4/rtc_api.c
index 61dfd2bb5e..1176bdf9ae 100644
--- a/libraries/mbed/targets/hal/TARGET_STM/TARGET_STM32L4/rtc_api.c
+++ b/libraries/mbed/targets/hal/TARGET_STM/TARGET_STM32L4/rtc_api.c
@@ -33,7 +33,9 @@
 
 #include "mbed_error.h"
 
+#if DEVICE_RTC_LSI
 static int rtc_inited = 0;
+#endif
 
 static RTC_HandleTypeDef RtcHandle;
 
@@ -43,8 +45,10 @@ void rtc_init(void)
     RCC_PeriphCLKInitTypeDef PeriphClkInitStruct = {0};
     uint32_t rtc_freq = 0;
 
+#if DEVICE_RTC_LSI
     if (rtc_inited) return;
     rtc_inited = 1;
+#endif
 
     RtcHandle.Instance = RTC;
 
@@ -58,6 +62,7 @@ void rtc_init(void)
     __HAL_RCC_BACKUPRESET_FORCE();
     __HAL_RCC_BACKUPRESET_RELEASE();
 
+#if !DEVICE_RTC_LSI
     // Enable LSE Oscillator
     RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSI | RCC_OSCILLATORTYPE_LSE;
     RCC_OscInitStruct.PLL.PLLState   = RCC_PLL_NONE; // Mandatory, otherwise the PLL is reconfigured!
@@ -69,24 +74,27 @@ void rtc_init(void)
         PeriphClkInitStruct.RTCClockSelection = RCC_RTCCLKSOURCE_LSE;
         HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct);
         rtc_freq = LSE_VALUE;
-    } else { // LSE didn't start, try with LSI
-        // Enable LSI clock
-        RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSI | RCC_OSCILLATORTYPE_LSE;
-        RCC_OscInitStruct.PLL.PLLState   = RCC_PLL_NONE; // Mandatory, otherwise the PLL is reconfigured!
-        RCC_OscInitStruct.LSEState       = RCC_LSE_OFF;
-        RCC_OscInitStruct.LSIState       = RCC_LSI_ON;
-        if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
-            error("Cannot initialize RTC with LSI\n");
-        }
-        // Connect LSI to RTC
-        PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_RTC;
-        PeriphClkInitStruct.RTCClockSelection = RCC_RTCCLKSOURCE_LSI;
-        if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK) {
-            error("Cannot initialize RTC with LSI\n");
-        }
-        // This value is LSI typical value. To be measured precisely using a timer input capture for example.
-        rtc_freq = 40000;
+    } else {
+	    error("Cannot initialize RTC with LSE\n");
     }
+#else	
+	// Enable LSI clock
+	RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSI | RCC_OSCILLATORTYPE_LSE;
+	RCC_OscInitStruct.PLL.PLLState   = RCC_PLL_NONE; // Mandatory, otherwise the PLL is reconfigured!
+	RCC_OscInitStruct.LSEState       = RCC_LSE_OFF;
+	RCC_OscInitStruct.LSIState       = RCC_LSI_ON;
+	if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
+		error("Cannot initialize RTC with LSI\n");
+	}
+	// Connect LSI to RTC
+	PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_RTC;
+	PeriphClkInitStruct.RTCClockSelection = RCC_RTCCLKSOURCE_LSI;
+	if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK) {
+		error("Cannot initialize RTC with LSI\n");
+	}
+	// This value is LSI typical value. To be measured precisely using a timer input capture for example.
+	rtc_freq = 40000;
+#endif
 
     // Check if RTC is already initialized
     if ((RTC->ISR & RTC_ISR_INITS) ==  RTC_ISR_INITS) return;
@@ -129,12 +137,22 @@ void rtc_free(void)
     RCC_OscInitStruct.LSEState       = RCC_LSE_OFF;
     HAL_RCC_OscConfig(&RCC_OscInitStruct);
 
+#if DEVICE_RTC_LSI
     rtc_inited = 0;
+#endif	
 }
 
 int rtc_isenabled(void)
 {
-    return rtc_inited;
+#if DEVICE_RTC_LSI
+  return rtc_inited;
+#else
+  if ((RTC->ISR & RTC_ISR_INITS) ==  RTC_ISR_INITS) {
+    return 1;
+  } else {
+    return 0;
+  }
+#endif
 }
 
 /*