diff --git a/lib/browser/api/dialog.js b/lib/browser/api/dialog.js
index 6669d8cab89a..3410618027fe 100644
--- a/lib/browser/api/dialog.js
+++ b/lib/browser/api/dialog.js
@@ -35,8 +35,9 @@ var parseArgs = function (window, options, callback, ...args) {
   }
 
   // Fallback to using very last argument as the callback function
-  if ((callback == null) && typeof args[args.length - 1] === 'function') {
-    callback = args[args.length - 1]
+  var lastArgument = args[args.length - 1]
+  if ((callback == null) && typeof lastArgument === 'function') {
+    callback = lastArgument
   }
 
   return [window, options, callback]