diff --git a/build/shared/lib/keywords.txt b/build/shared/lib/keywords.txt
index 730de4e7575..cc7ceb499f6 100644
--- a/build/shared/lib/keywords.txt
+++ b/build/shared/lib/keywords.txt
@@ -179,6 +179,7 @@ parseInt	KEYWORD2
 parseFloat	KEYWORD2
 readBytes	KEYWORD2
 readBytesUntil	KEYWORD2
+waitForBufferSpace  KEYWORD2 
 
 setup	KEYWORD3	Setup
 loop	KEYWORD3	Loop
diff --git a/hardware/arduino/cores/arduino/HardwareSerial.cpp b/hardware/arduino/cores/arduino/HardwareSerial.cpp
index b5992ad6fe3..cd765e92a97 100644
--- a/hardware/arduino/cores/arduino/HardwareSerial.cpp
+++ b/hardware/arduino/cores/arduino/HardwareSerial.cpp
@@ -289,6 +289,7 @@ HardwareSerial::HardwareSerial(ring_buffer *rx_buffer, ring_buffer *tx_buffer,
   _rxcie = rxcie;
   _udrie = udrie;
   _u2x = u2x;
+  _serial_buffer_wait = 0x1; //by default, wait for space.
 }
 
 // Public Methods //////////////////////////////////////////////////////////////
@@ -384,11 +385,14 @@ size_t HardwareSerial::write(uint8_t c)
 {
   int i = (_tx_buffer->head + 1) % SERIAL_BUFFER_SIZE;
 	
-  // If the output buffer is full, there's nothing for it other than to 
-  // wait for the interrupt handler to empty it a bit
-  // ???: return 0 here instead?
-  while (i == _tx_buffer->tail)
+  // If the output buffer is full, there's two options. Either quit or wait for interrupt handler to make space. User decides.
+ if(_serial_buffer_wait == 1) {
+	while (i == _tx_buffer->tail)
     ;
+	} else {
+	if(i == _tx_buffer->tail) { return 0; }
+	}
+
 	
   _tx_buffer->buffer[_tx_buffer->head] = c;
   _tx_buffer->head = i;
@@ -398,6 +402,9 @@ size_t HardwareSerial::write(uint8_t c)
   return 1;
 }
 
+void HardwareSerial::waitForBufferSpace(uint8_t v) {
+	_serial_buffer_wait = v;
+}
 // Preinstantiate Objects //////////////////////////////////////////////////////
 
 #if defined(UBRRH) && defined(UBRRL)
diff --git a/hardware/arduino/cores/arduino/HardwareSerial.h b/hardware/arduino/cores/arduino/HardwareSerial.h
index 176abe1e20b..6a3728fc4e2 100644
--- a/hardware/arduino/cores/arduino/HardwareSerial.h
+++ b/hardware/arduino/cores/arduino/HardwareSerial.h
@@ -43,6 +43,7 @@ class HardwareSerial : public Stream
     uint8_t _rxcie;
     uint8_t _udrie;
     uint8_t _u2x;
+    uint8_t _serial_buffer_wait;
   public:
     HardwareSerial(ring_buffer *rx_buffer, ring_buffer *tx_buffer,
       volatile uint8_t *ubrrh, volatile uint8_t *ubrrl,
@@ -57,6 +58,7 @@ class HardwareSerial : public Stream
     virtual void flush(void);
     virtual size_t write(uint8_t);
     using Print::write; // pull in write(str) and write(buf, size) from Print
+    virtual void waitForBufferSpace(uint8_t);
 };
 
 #if defined(UBRRH) || defined(UBRR0H)