diff --git a/cores/arduino/stm32/twi.c b/cores/arduino/stm32/twi.c
index 2c3ad39804..44c8e9fc34 100644
--- a/cores/arduino/stm32/twi.c
+++ b/cores/arduino/stm32/twi.c
@@ -548,14 +548,14 @@ void HAL_I2C_AddrCallback(I2C_HandleTypeDef *hi2c, uint8_t TransferDirection, ui
       if(obj->i2c_onSlaveTransmit != NULL) {
         obj->i2c_onSlaveTransmit();
       }
-      HAL_I2C_Slave_Sequential_Transmit_IT(hi2c, obj->i2cTxRxBuffer,
+      HAL_I2C_Slave_Sequential_Transmit_IT(hi2c, (uint8_t *) obj->i2cTxRxBuffer,
                                            obj->i2cTxRxBufferSize, I2C_LAST_FRAME);
     } else {
       obj->slaveRxNbData = 0;
       obj->slaveMode = SLAVE_MODE_RECEIVE;
       /*  We don't know in advance how many bytes will be sent by master so
        *  we'll fetch one by one until master ends the sequence */
-      HAL_I2C_Slave_Sequential_Receive_IT(hi2c, &(obj->i2cTxRxBuffer[obj->slaveRxNbData]),
+      HAL_I2C_Slave_Sequential_Receive_IT(hi2c, (uint8_t *) &(obj->i2cTxRxBuffer[obj->slaveRxNbData]),
                                           1, I2C_NEXT_FRAME);
     }
   }
@@ -576,7 +576,7 @@ void HAL_I2C_ListenCpltCallback(I2C_HandleTypeDef *hi2c)
   if((obj->i2c_onSlaveReceive != NULL) &&
     (obj->slaveMode == SLAVE_MODE_RECEIVE)) {
     if(obj->slaveRxNbData != 0) {
-      obj->i2c_onSlaveReceive(obj->i2cTxRxBuffer, obj->slaveRxNbData);
+      obj->i2c_onSlaveReceive((uint8_t *) obj->i2cTxRxBuffer, obj->slaveRxNbData);
     }
   }
   obj->slaveMode = SLAVE_MODE_LISTEN;
@@ -601,7 +601,7 @@ void HAL_I2C_SlaveRxCpltCallback(I2C_HandleTypeDef *hi2c)
   }
   /* Restart interrupt mode for next Byte */
   if(obj->slaveMode == SLAVE_MODE_RECEIVE) {
-      HAL_I2C_Slave_Sequential_Receive_IT(hi2c, &(obj->i2cTxRxBuffer[obj->slaveRxNbData]),
+      HAL_I2C_Slave_Sequential_Receive_IT(hi2c, (uint8_t *) &(obj->i2cTxRxBuffer[obj->slaveRxNbData]),
                                           1, I2C_NEXT_FRAME);
   }
 }