diff --git a/targets/TARGET_STM/TARGET_STM32L0/device/stm32l0xx_hal_crc.c b/targets/TARGET_STM/TARGET_STM32L0/device/stm32l0xx_hal_crc.c
index b5b778e00e..80532e08f1 100644
--- a/targets/TARGET_STM/TARGET_STM32L0/device/stm32l0xx_hal_crc.c
+++ b/targets/TARGET_STM/TARGET_STM32L0/device/stm32l0xx_hal_crc.c
@@ -421,7 +421,14 @@ uint32_t HAL_CRC_Calculate(CRC_HandleTypeDef *hcrc, uint32_t pBuffer[], uint32_t
   return temp;
 }
 
+#if __GNUC__
+#    define MAY_ALIAS __attribute__ ((__may_alias__))
+#else
+#    define MAY_ALIAS
+#endif
 
+typedef __IO uint8_t  MAY_ALIAS uint8_io_t;
+typedef __IO uint16_t MAY_ALIAS uint16_io_t;
 
 /**
   * @}
@@ -486,16 +493,16 @@ static uint32_t CRC_Handle_8(CRC_HandleTypeDef *hcrc, uint8_t pBuffer[], uint32_
    {
      if  (BufferLength%4U == 1U)
      {
-       *(uint8_t volatile*) (&hcrc->Instance->DR) = pBuffer[4U*i];
+       *(uint8_io_t*) (&hcrc->Instance->DR) = pBuffer[4U*i];
      }
      if  (BufferLength%4U == 2U)
      {
-       *(uint16_t volatile*) (&hcrc->Instance->DR) = ((uint32_t)pBuffer[4U*i]<<8U) | (uint32_t)pBuffer[4U*i+1U];
+       *(uint16_io_t*) (&hcrc->Instance->DR) = ((uint32_t)pBuffer[4U*i]<<8U) | (uint32_t)pBuffer[4U*i+1U];
      }
      if  (BufferLength%4U == 3U)
      {
-       *(uint16_t volatile*) (&hcrc->Instance->DR) = ((uint32_t)pBuffer[4U*i]<<8U) | (uint32_t)pBuffer[4U*i+1U];
-       *(uint8_t volatile*) (&hcrc->Instance->DR) = pBuffer[4U*i+2U];
+       *(uint16_io_t*) (&hcrc->Instance->DR) = ((uint32_t)pBuffer[4U*i]<<8U) | (uint32_t)pBuffer[4U*i+1U];
+       *(uint8_io_t*) (&hcrc->Instance->DR) = pBuffer[4U*i+2U];
      }
    }
   
@@ -524,7 +531,7 @@ static uint32_t CRC_Handle_16(CRC_HandleTypeDef *hcrc, uint16_t pBuffer[], uint3
   }
   if ((BufferLength%2U) != 0U)
   {
-       *(uint16_t volatile*) (&hcrc->Instance->DR) = pBuffer[2U*i];
+       *(uint16_io_t*) (&hcrc->Instance->DR) = pBuffer[2U*i];
   }
    
   /* Return the CRC computed value */ 
diff --git a/targets/TARGET_STM/TARGET_STM32L0/device/stm32l0xx_ll_spi.h b/targets/TARGET_STM/TARGET_STM32L0/device/stm32l0xx_ll_spi.h
index 2e693f54ab..e4b962184e 100644
--- a/targets/TARGET_STM/TARGET_STM32L0/device/stm32l0xx_ll_spi.h
+++ b/targets/TARGET_STM/TARGET_STM32L0/device/stm32l0xx_ll_spi.h
@@ -1121,6 +1121,14 @@ __STATIC_INLINE void LL_SPI_TransmitData8(SPI_TypeDef *SPIx, uint8_t TxData)
   *((__IO uint8_t *)&SPIx->DR) = TxData;
 }
 
+#if __GNUC__
+#    define MAY_ALIAS __attribute__ ((__may_alias__))
+#else
+#    define MAY_ALIAS
+#endif
+
+typedef __IO uint16_t MAY_ALIAS uint16_io_t;
+
 /**
   * @brief  Write 16-Bits in the data register
   * @rmtoll DR           DR            LL_SPI_TransmitData16
@@ -1130,7 +1138,7 @@ __STATIC_INLINE void LL_SPI_TransmitData8(SPI_TypeDef *SPIx, uint8_t TxData)
   */
 __STATIC_INLINE void LL_SPI_TransmitData16(SPI_TypeDef *SPIx, uint16_t TxData)
 {
-  *((__IO uint16_t *)&SPIx->DR) = TxData;
+  *((uint16_io_t*)&SPIx->DR) = TxData;
 }
 
 /**
diff --git a/targets/TARGET_STM/TARGET_STM32L0/serial_device.c b/targets/TARGET_STM/TARGET_STM32L0/serial_device.c
index 63cf3154de..dad4bef293 100644
--- a/targets/TARGET_STM/TARGET_STM32L0/serial_device.c
+++ b/targets/TARGET_STM/TARGET_STM32L0/serial_device.c
@@ -46,7 +46,7 @@ UART_HandleTypeDef uart_handlers[UART_NUM];
 static uart_irq_handler irq_handler;
 
 // Defined in serial_api.c
-inline int8_t get_uart_index(UARTName uart_name);
+extern int8_t get_uart_index(UARTName uart_name);
 
 /******************************************************************************
  * INTERRUPTS HANDLING