diff --git a/lib/socket.js b/lib/socket.js
index 7e13a6125..8fd0dfd14 100644
--- a/lib/socket.js
+++ b/lib/socket.js
@@ -220,7 +220,7 @@ Socket.prototype.onevent = function(packet){
   var args = packet.data || [];
   debug('emitting event %j', args);
 
-  if (packet.id) {
+  if (null != packet.id) {
     debug('attaching ack callback to event');
     args.push(this.ack(packet.id));
   }