diff --git a/src/js/vapi-background.js b/src/js/vapi-background.js
index 2996836..bccf934 100644
--- a/src/js/vapi-background.js
+++ b/src/js/vapi-background.js
@@ -695,7 +695,7 @@ if (self.chrome) {
 
                 var listener = connector(request.message.msg, sender, callback);
 
-                if (listener === null) {
+                if (listener === vAPI.messaging.UNHANDLED) {
                     listener = vAPI.messaging.listeners[request.message.portName];
 
                     if (typeof listener === 'function') {