diff --git a/js/xpconnect/tests/chrome/Makefile.in b/js/xpconnect/tests/chrome/Makefile.in
index e71ca33e1d84..e6df9832aed4 100644
--- a/js/xpconnect/tests/chrome/Makefile.in
+++ b/js/xpconnect/tests/chrome/Makefile.in
@@ -35,7 +35,10 @@ MOCHITEST_CHROME_FILES = \
 		test_bug743843.xul \
 		test_bug758563.xul \
 		test_bug760076.xul \
+		test_bug760109.xul \
 		test_bug763343.xul \
+		test_bug771429.xul \
+		test_bug773962.xul \
 		test_APIExposer.xul \
 		test_chrometoSource.xul \
 		outoflinexulscript.js \
@@ -55,8 +58,6 @@ MOCHITEST_CHROME_FILES = \
 		test_weakmaps.xul \
 		test_weakref.xul \
 		test_wrappers.xul \
-		test_bug771429.xul \
-		test_bug773962.xul \
 		$(NULL)
 
 # Disabled until this test gets updated to test the new proxy based
diff --git a/js/xpconnect/tests/chrome/test_bug760109.xul b/js/xpconnect/tests/chrome/test_bug760109.xul
new file mode 100644
index 000000000000..0ac488797af3
--- /dev/null
+++ b/js/xpconnect/tests/chrome/test_bug760109.xul
@@ -0,0 +1,89 @@
+<?xml version="1.0"?>
+<?xml-stylesheet type="text/css" href="chrome://global/skin"?>
+<?xml-stylesheet type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"?>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=760109
+-->
+<window title="Mozilla Bug 760109"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=760109"
+     target="_blank">Mozilla Bug 760109</a>
+  </body>
+
+  <!-- test code goes here -->
+  <script type="application/javascript">
+  <![CDATA[
+
+  /** Test for COW prototype remapping.**/
+
+  // This gets decompiled and run inside the sandbox.
+  function sandboxCode() {
+
+    // Check that COWs for objects with standard prototypes use the standard
+    // prototype in the home compartment.
+    ok(Object.getPrototypeOf(chromeArray) === Array.prototype,
+       "Array prototype remapped properly");
+    var protoProto = Object.getPrototypeOf(Object.getPrototypeOf(chromeObject));
+    ok(protoProto === Object.prototype,
+       "Object prototype remapped properly");
+
+    // Check |constructor|. The semantics of this weird for the case of an
+    // object with a custom chrome-implemented prototype, because we'll end up
+    // bouncing up the prototype chain to Object, even though that's not fully
+    // accurate. It's unlikely to be a problem though, so we just verify that
+    // it does what we expect.
+    ok(chromeObject.constructor === Object, "Object constructor does what we expect");
+    ok(chromeArray.constructor === Array, "Array constructor remapped properly");
+
+    // We should be able to .forEach on the Array.
+    var concat = '';
+    chromeArray.forEach(function(val) { concat += val; });
+    is(concat, 'abz', "Should be able to .forEach COW-ed Array");
+
+    // Try other Array operations.
+    is(chromeArray.indexOf('b'), 1, "indexOf works correctly");
+    is(chromeArray.join(''), concat, "join works correctly");
+    is(chromeArray.slice(1).join(''), 'bz', "slice works correctly");
+
+    // Try some operations that modify the array.
+    is(chromeArray.pop(), 'z', "Able to call pop");
+    is(chromeArray.push('z'), 3, "Able to call push");
+    chromeArray.reverse();
+    is(chromeArray.join(''), 'zba', "Able to call reverse");
+    chromeArray.sort();
+    is(chromeArray.join(''), 'abz', "Able to call sort");
+
+    // We should be able to .hasOwnProperty on the Object, and have
+    // it filter the objects we can see.
+    ok(chromeObject.hasOwnProperty('foo'), "Should see r property");
+    ok(!chromeObject.hasOwnProperty('bar'), "Shouldn't see non-exposed property");
+    ok(chromeObject.hasOwnProperty('baz'), "Should see rw property");
+  }
+
+  // We use a constructor to create the test object so that there's an
+  // intermediate object on the prototype chain between the instance and the
+  // standard prototype.
+  function SomeConstructor() {
+    this.foo = 2;
+    this.bar = 3;
+    this.baz = 4;
+    this.__exposedProps__ = {foo: 'r', baz: 'rw'};
+  }
+  SomeConstructor.prototype.__exposedProps__ = {};
+
+  const Cu = Components.utils;
+  var sb = new Cu.Sandbox('http://www.example.org');
+  sb.chromeArray = ['a', 'b', 'z'];
+  sb.chromeArray.__exposedProps__ = {};
+  sb.chromeObject = new SomeConstructor();
+  sb.ok = ok;
+  sb.is = is;
+  Cu.evalInSandbox('(' + sandboxCode.toSource() + ')();', sb);
+
+  ]]>
+  </script>
+</window>
diff --git a/js/xpconnect/tests/chrome/test_cows.xul b/js/xpconnect/tests/chrome/test_cows.xul
index 9a73529c8263..fe6dc69a1f78 100644
--- a/js/xpconnect/tests/chrome/test_cows.xul
+++ b/js/xpconnect/tests/chrome/test_cows.xul
@@ -92,7 +92,7 @@ function COWTests() {
     //is(cow.foo, undefined, "one test to rule them all");
     //return;
 
-    const PROPS_TO_TEST = ['foo', 'bar', '__proto__', 'prototype', 'constructor'];
+    const PROPS_TO_TEST = ['foo', 'bar', 'prototype'];
 
     var empty = {};
     // Once we flip the default for __exposedProps__, this should behave
