diff --git a/js/tests/js1_5/Regress/regress-340199.js b/js/tests/js1_5/Regress/regress-340199.js
new file mode 100755
index 000000000000..41a6af3b69bc
--- /dev/null
+++ b/js/tests/js1_5/Regress/regress-340199.js
@@ -0,0 +1,63 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is JavaScript Engine testing utilities.
+ *
+ * The Initial Developer of the Original Code is
+ * Mozilla Foundation.
+ * Portions created by the Initial Developer are Copyright (C) 2006
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s): Blake Kaplan
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+//-----------------------------------------------------------------------------
+var bug = 340199;
+var summary = 'User-defined __iterator__ can be called through XPCNativeWrappers';
+var actual = 'Not called';
+var expect = 'Not called';
+
+printBugNumber (bug);
+printStatus (summary);
+
+if (typeof window != 'undefined' &&
+    typeof XPCNativeWrapper != 'undefined')
+{
+  Object.prototype.__iterator__ = function () { actual = "User code called"; writeLineToLog(actual); };
+  for (var i in XPCNativeWrapper(window)) 
+  {
+    try 
+    { 
+      writeLineToLog(i);
+    } 
+    catch(ex)
+    {
+      writeLineToLog(ex);
+    }
+  }
+}
+  
+reportCompare(expect, actual, summary);