--- a/js/xpconnect/tests/chrome/test_bug760109.xul
+++ b/js/xpconnect/tests/chrome/test_bug760109.xul
@@ -75,17 +75,21 @@ https://bugzilla.mozilla.org/show_bug.cg
     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.chromeArray.__exposedProps__ = { length: 'rw' };
+  for (var i = 0; i < 10; ++i) {
+    sb.chromeArray.__exposedProps__[i] = 'rw';
+  }
+
   sb.chromeObject = new SomeConstructor();
   sb.ok = ok;
   sb.is = is;
   Cu.evalInSandbox('(' + sandboxCode.toSource() + ')();', sb);
 
   ]]>
   </script>
 </window>