diff --git a/lib/shadowsocks/local.js b/lib/shadowsocks/local.js
index 22131b4..2434353 100644
--- a/lib/shadowsocks/local.js
+++ b/lib/shadowsocks/local.js
@@ -64,7 +64,7 @@
   createServer = function(serverAddr, serverPort, port, key, method, timeout, local_address) {
     var getServer, server, udpServer;
     if (local_address == null) {
-      local_address = null;
+      local_address = '127.0.0.1';
     }
     udpServer = udpRelay.createServer(local_address, port, serverAddr, serverPort, key, method, timeout, true);
     getServer = function() {
diff --git a/src/local.coffee b/src/local.coffee
index b9ee4e8..ccc17db 100644
--- a/src/local.coffee
+++ b/src/local.coffee
@@ -46,7 +46,7 @@ inetAton = (ipStr) ->
 
 connections = 0
 
-createServer = (serverAddr, serverPort, port, key, method, timeout, local_address=null) ->
+createServer = (serverAddr, serverPort, port, key, method, timeout, local_address='127.0.0.1') ->
   
   udpServer = udpRelay.createServer(local_address, port, serverAddr, serverPort, key, method, timeout, true)