diff -r 000000000000 -r 6474c204b198 modules/libjar/test/unit/test_dirjar_bug525755.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/modules/libjar/test/unit/test_dirjar_bug525755.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,25 @@
+/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et: */
+/* 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/. */
+
+// Check that we refuse to open weird files
+function run_test() {
+  const Cc = Components.classes;
+  const Ci = Components.interfaces;
+  // open a bogus file
+  var file = do_get_file("/");
+
+  var zipreader = Cc["@mozilla.org/libjar/zip-reader;1"].
+                  createInstance(Ci.nsIZipReader);
+  var failed = false;
+  try {
+    zipreader.open(file);
+  } catch (e) {
+    failed = true;
+  }
+  do_check_true(failed);
+  zipreader = null;
+}
+