diff --git a/phpgwapi/js/jsapi/egw_message.js b/phpgwapi/js/jsapi/egw_message.js
index fa3d2783d5..6361471191 100644
--- a/phpgwapi/js/jsapi/egw_message.js
+++ b/phpgwapi/js/jsapi/egw_message.js
@@ -119,7 +119,7 @@ egw.extend('message', egw.MODULE_WND_LOCAL, function(_app, _wnd)
 		{
 			var popup = false;
 			try {
-				if (_wnd.opener && typeof _wnd.opener.top.egw == 'object')
+				if (_wnd.opener && typeof _wnd.opener.top.egw == 'function')
 				{
 					popup = true;
 				}