diff --git a/meta/crx/vapi-background.js b/meta/crx/vapi-background.js
index 6cd19b2..331e2bf 100644
--- a/meta/crx/vapi-background.js
+++ b/meta/crx/vapi-background.js
@@ -287,7 +287,7 @@ vAPI.messaging.setup = function(defaultHandler) {
     }
 
     if ( typeof defaultHandler !== 'function' ) {
-        defaultHandler = function(){ return null; };
+        defaultHandler = function(){ return vAPI.messaging.UNHANDLED; };
     }
     this.defaultHandler = defaultHandler;