diff --git a/libraries/mbed/api/SerialBase.h b/libraries/mbed/api/SerialBase.h
index fd5bc3dd1d..eecf98bc69 100644
--- a/libraries/mbed/api/SerialBase.h
+++ b/libraries/mbed/api/SerialBase.h
@@ -135,7 +135,7 @@ public:
      *  @param callback The event callback function
      *  @param event    The logical OR of TX events
      */
-    int write(uint8_t *buffer, int length, const event_callback_t& callback, int event = SERIAL_EVENT_TX_COMPLETE);
+    int write(const uint8_t *buffer, int length, const event_callback_t& callback, int event = SERIAL_EVENT_TX_COMPLETE);
 
     /** Begin asynchronous write using 16bit buffer. The completition invokes registered TX event callback
      *
@@ -144,7 +144,7 @@ public:
      *  @param callback The event callback function
      *  @param event    The logical OR of TX events
      */
-    int write(uint16_t *buffer, int length, const event_callback_t& callback, int event = SERIAL_EVENT_TX_COMPLETE);
+    int write(const uint16_t *buffer, int length, const event_callback_t& callback, int event = SERIAL_EVENT_TX_COMPLETE);
 
     /** Abort the on-going write transfer
      */
@@ -190,7 +190,7 @@ public:
 
 protected:
     void start_read(void *buffer, int buffer_size, char buffer_width, const event_callback_t& callback, int event, unsigned char char_match);
-    void start_write(void *buffer, int buffer_size, char buffer_width, const event_callback_t& callback, int event);
+    void start_write(const void *buffer, int buffer_size, char buffer_width, const event_callback_t& callback, int event);
     void interrupt_handler_asynch(void);
 #endif
 
diff --git a/libraries/mbed/common/SerialBase.cpp b/libraries/mbed/common/SerialBase.cpp
index 2d5ea8c4c5..880a0212e6 100644
--- a/libraries/mbed/common/SerialBase.cpp
+++ b/libraries/mbed/common/SerialBase.cpp
@@ -110,7 +110,7 @@ void SerialBase::set_flow_control(Flow type, PinName flow1, PinName flow2) {
 
 #if DEVICE_SERIAL_ASYNCH
 
-int SerialBase::write(uint8_t *buffer, int length, const event_callback_t& callback, int event)
+int SerialBase::write(const uint8_t *buffer, int length, const event_callback_t& callback, int event)
 {
     if (serial_tx_active(&_serial)) {
         return -1; // transaction ongoing
@@ -119,7 +119,7 @@ int SerialBase::write(uint8_t *buffer, int length, const event_callback_t& callb
     return 0;
 }
 
-int SerialBase::write(uint16_t *buffer, int length, const event_callback_t& callback, int event)
+int SerialBase::write(const uint16_t *buffer, int length, const event_callback_t& callback, int event)
 {
     if (serial_tx_active(&_serial)) {
         return -1; // transaction ongoing
@@ -128,7 +128,7 @@ int SerialBase::write(uint16_t *buffer, int length, const event_callback_t& call
     return 0;
 }
 
-void SerialBase::start_write(void *buffer, int buffer_size, char buffer_width, const event_callback_t& callback, int event)
+void SerialBase::start_write(const void *buffer, int buffer_size, char buffer_width, const event_callback_t& callback, int event)
 {
     _tx_callback = callback;
 
diff --git a/libraries/mbed/hal/serial_api.h b/libraries/mbed/hal/serial_api.h
index eee7308cc2..6cf9a4bb5a 100644
--- a/libraries/mbed/hal/serial_api.h
+++ b/libraries/mbed/hal/serial_api.h
@@ -237,7 +237,7 @@ void serial_set_flow_control(serial_t *obj, FlowControl type, PinName rxflow, Pi
  * @param hint      A suggestion for how to use DMA with this transfer
  * @return Returns number of data transfered, or 0 otherwise
  */
-int serial_tx_asynch(serial_t *obj, void *tx, size_t tx_length, uint8_t tx_width, uint32_t handler, uint32_t event, DMAUsage hint);
+int serial_tx_asynch(serial_t *obj, const void *tx, size_t tx_length, uint8_t tx_width, uint32_t handler, uint32_t event, DMAUsage hint);
 
 /** Begin asynchronous RX transfer (enable interrupt for data collecting)
  *  The used buffer is specified in the serial object - rx_buff
diff --git a/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/serial_api.c b/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/serial_api.c
index d2bcf933d6..2094976fa7 100644
--- a/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/serial_api.c
+++ b/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/serial_api.c
@@ -1262,14 +1262,14 @@ void serial_set_char_match(serial_t *obj, uint8_t char_match)
  * @param hint A suggestion for how to use DMA with this transfer
  * @return Returns number of data transfered, or 0 otherwise
  */
-int serial_tx_asynch(serial_t *obj, void *tx, size_t tx_length, uint8_t tx_width, uint32_t handler, uint32_t event, DMAUsage hint)
+int serial_tx_asynch(serial_t *obj, const void *tx, size_t tx_length, uint8_t tx_width, uint32_t handler, uint32_t event, DMAUsage hint)
 {
     // Check that a buffer has indeed been set up
     MBED_ASSERT(tx != (void*)0);
     if(tx_length == 0) return 0;
 
     // Set up buffer
-    serial_tx_buffer_set(obj, tx, tx_length, tx_width);
+    serial_tx_buffer_set(obj, (void *)tx, tx_length, tx_width);
 
     // Set up events
     serial_tx_enable_event(obj, SERIAL_EVENT_TX_ALL, false);