diff --git a/libraries/ESP8266WiFi/src/WiFiUdp.cpp b/libraries/ESP8266WiFi/src/WiFiUdp.cpp
index ecf3f858f..1a98f83b5 100644
--- a/libraries/ESP8266WiFi/src/WiFiUdp.cpp
+++ b/libraries/ESP8266WiFi/src/WiFiUdp.cpp
@@ -74,7 +74,7 @@ uint8_t WiFiUDP::begin(uint16_t port)
     return (_ctx->listen(addr, port)) ? 1 : 0;
 }
 
-uint8_t WiFiUDP::beginMulticast(IPAddress multicast, uint16_t port)
+uint8_t WiFiUDP::beginMulticast(IPAddress interfaceAddr, IPAddress multicast, uint16_t port)
 {
     if (_ctx)
     {
@@ -84,7 +84,7 @@ uint8_t WiFiUDP::beginMulticast(IPAddress multicast, uint16_t port)
     
 
     ip_addr_t ifaddr;
-    ifaddr.addr = (uint32_t) WiFi.localIP();
+    ifaddr.addr = (uint32_t) interfaceAddr;
     ip_addr_t multicast_addr;
     multicast_addr.addr = (uint32_t) multicast;
 
diff --git a/libraries/ESP8266WiFi/src/WiFiUdp.h b/libraries/ESP8266WiFi/src/WiFiUdp.h
index a5d5586d5..06b39d0fe 100644
--- a/libraries/ESP8266WiFi/src/WiFiUdp.h
+++ b/libraries/ESP8266WiFi/src/WiFiUdp.h
@@ -42,7 +42,7 @@ public:
 
   virtual uint8_t begin(uint16_t port);	// initialize, start listening on specified port. Returns 1 if successful, 0 if there are no sockets available to use
   virtual void stop();  // Finish with the UDP socket
-  uint8_t beginMulticast(IPAddress multicast, uint16_t port); // connect to a multicast group and listen on the given port
+  uint8_t beginMulticast(IPAddress interfaceAddr, IPAddress multicast, uint16_t port); // connect to a multicast group and listen on the given port
 
   // Sending UDP packets
   
diff --git a/libraries/ESP8266mDNS/ESP8266mDNS.cpp b/libraries/ESP8266mDNS/ESP8266mDNS.cpp
index a4a9f3781..2206c92ac 100644
--- a/libraries/ESP8266mDNS/ESP8266mDNS.cpp
+++ b/libraries/ESP8266mDNS/ESP8266mDNS.cpp
@@ -149,7 +149,7 @@ bool MDNSResponder::begin(const char* domain, IPAddress addr, uint32_t ttlSecond
   
   // Open the MDNS socket if it isn't already open.
   if (!_mdnsConn) {
-    if (!_mdnsConn.beginMulticast(IPAddress(224, 0, 0, 251), 5353)) {
+    if (!_mdnsConn.beginMulticast(addr, IPAddress(224, 0, 0, 251), 5353)) {
       return false;
     }
   }