diff --git a/lib/io/ioserver.js b/lib/io/ioserver.js
index 72ef6ff8..a00e7eec 100644
--- a/lib/io/ioserver.js
+++ b/lib/io/ioserver.js
@@ -127,6 +127,13 @@ function addTypecheckedFunctions(sock) {
  */
 function handleConnection(sock) {
     var ip = sock.request.connection.remoteAddress;
+    if (!ip) {
+        socket.emit("kick", {
+            reason: "Your IP address could not be determined from the socket connection.  See https://github.com/Automattic/socket.io/issues/1387#issuecomment-48425088 for details"
+        });
+        return;
+    }
+
     if (net.isIPv6(ip)) {
         ip = util.expandIPv6(ip);
     }