diff --git a/hardware/arduino/avr/cores/arduino/Udp.h b/hardware/arduino/avr/cores/arduino/Udp.h
index dc5644b9df2..89f31c676da 100644
--- a/hardware/arduino/avr/cores/arduino/Udp.h
+++ b/hardware/arduino/avr/cores/arduino/Udp.h
@@ -41,7 +41,8 @@
 class UDP : public Stream {
 
 public:
-  virtual uint8_t begin(uint16_t) =0;	// initialize, start listening on specified port. Returns 1 if successful, 0 if there are no sockets available to use
+  virtual uint8_t begin(uint16_t) =0;  // initialize, start listening on specified port. Returns 1 if successful, 0 if there are no sockets available to use
+  virtual uint8_t beginMulticast(IPAddress, uint16_t) { return 0; }  // initialize, start listening on specified multicast IP address and port. Returns 1 if successful, 0 on failure
   virtual void stop() =0;  // Finish with the UDP socket
 
   // Sending UDP packets
diff --git a/hardware/arduino/sam/cores/arduino/Udp.h b/hardware/arduino/sam/cores/arduino/Udp.h
index dc5644b9df2..89f31c676da 100644
--- a/hardware/arduino/sam/cores/arduino/Udp.h
+++ b/hardware/arduino/sam/cores/arduino/Udp.h
@@ -41,7 +41,8 @@
 class UDP : public Stream {
 
 public:
-  virtual uint8_t begin(uint16_t) =0;	// initialize, start listening on specified port. Returns 1 if successful, 0 if there are no sockets available to use
+  virtual uint8_t begin(uint16_t) =0;  // initialize, start listening on specified port. Returns 1 if successful, 0 if there are no sockets available to use
+  virtual uint8_t beginMulticast(IPAddress, uint16_t) { return 0; }  // initialize, start listening on specified multicast IP address and port. Returns 1 if successful, 0 on failure
   virtual void stop() =0;  // Finish with the UDP socket
 
   // Sending UDP packets