diff --git a/AppKit/CPApplication.j b/AppKit/CPApplication.j
index 0593c6f0d..bfdefec28 100644
--- a/AppKit/CPApplication.j
+++ b/AppKit/CPApplication.j
@@ -270,7 +270,7 @@ CPRunContinuesResponse  = -1002;
         postNotificationName:CPApplicationWillFinishLaunchingNotification
         object:self];
 
-    var filename = window.cpOpeningFilename(),
+    var filename = window.cpOpeningFilename && window.cpOpeningFilename(),
         needsUntitled = !!_documentController;
 
     if ([filename length])