diff -r 000000000000 -r 6474c204b198 js/src/tests/js1_5/Regress/regress-165201.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/js1_5/Regress/regress-165201.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,55 @@
+/* -*- 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 = 165201;
+var summary = '';
+var actual = '';
+var expect = '';
+
+
+summary = 'RegExp.prototype.toSource should not affect RegExp.prototype.toString';
+
+printBugNumber(BUGNUMBER);
+printStatus (summary);
+
+/*
+ * Define function returning a regular expression literal
+ * and override RegExp.prototype.toSource
+ */
+
+function f()
+{
+  return /abc/;
+}
+
+RegExp.prototype.toSource = function() { return 'Hi there'; };
+
+expect = -1;
+actual = f.toString().indexOf('Hi there');
+
+reportCompare(expect, actual, summary);
+
+/*
+ * Define function returning an array literal
+ * and override RegExp.prototype.toSource
+ */
+summary = 'Array.prototype.toSource should not affect Array.prototype.toString';
+printBugNumber(BUGNUMBER);
+printStatus (summary);
+
+function g()
+{
+  return [1,2,3];
+}
+
+Array.prototype.toSource = function() { return 'Hi there'; }
+
+  expect = -1;
+actual = g.toString().indexOf('Hi there');
+
+reportCompare(expect, actual, summary);
+
+