diff --git a/lib/js/src/thrift.js b/lib/js/src/thrift.js
index 1a11871..5d420a2 100644
--- a/lib/js/src/thrift.js
+++ b/lib/js/src/thrift.js
@@ -572,18 +572,11 @@
           var clientCallback = callback;
           return function(msg) {
             self.setRecvBuffer(msg);
-            clientCallback();
+            if (clientCallback) {
+                clientCallback();
+            }
           };
         }()));
-        if(callback) {
-          this.callbacks.push((function() {
-            var clientCallback = callback;
-            return function(msg) {
-              self.setRecvBuffer(msg);
-              clientCallback();
-            };
-          }()));
-        }
       } else {
         //Queue the send to go out __onOpen
         this.send_pending.push({