diff --git a/targets/TARGET_STM/serial_api.c b/targets/TARGET_STM/serial_api.c
index 37c848664e..3dbd1e26c4 100644
--- a/targets/TARGET_STM/serial_api.c
+++ b/targets/TARGET_STM/serial_api.c
@@ -536,7 +536,9 @@ HAL_StatusTypeDef init_uart(serial_t *obj)
 #if defined(LPUART1_BASE)
     if (huart->Instance == LPUART1) {
         if (obj_s->baudrate <= 9600) {
+#if ((MBED_CONF_TARGET_LPUART_CLOCK_SOURCE) & USE_LPUART_CLK_LSE)            
             HAL_UARTEx_EnableClockStopMode(huart);
+#endif            
             HAL_UARTEx_EnableStopMode(huart);
         } else {
             HAL_UARTEx_DisableClockStopMode(huart);