diff -r 000000000000 -r 6474c204b198 js/src/tests/js1_5/Regress/regress-506567.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/js1_5/Regress/regress-506567.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,45 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 506567;
+var summary = 'Do not crash with watched variables';
+var actual = '';
+var expect = '';
+
+
+//-----------------------------------------------------------------------------
+test();
+//-----------------------------------------------------------------------------
+
+function test()
+{
+  enterFunc ('test');
+  printBugNumber(BUGNUMBER);
+  printStatus (summary);
+
+  if (typeof clearInterval == 'undefined')
+  {
+    clearInterval = (function () {});
+  }
+
+  var obj = new Object();
+  obj.test = null;
+  obj.watch("test", (function(prop, oldval, newval)
+    {
+      if(false)
+      {
+        var test = newval % oldval;
+        var func = (function(){clearInterval(myInterval);});
+      }
+    }));
+
+  obj.test = 'null';
+  print(obj.test);
+
+  reportCompare(expect, actual, summary);
+
+  exitFunc ('test');
+}