diff --git a/mozilla/testing/mochitest/tests/index.html b/mozilla/testing/mochitest/tests/index.html
index dc6850e9dd4..b5e95bf4581 100644
--- a/mozilla/testing/mochitest/tests/index.html
+++ b/mozilla/testing/mochitest/tests/index.html
@@ -67,6 +67,7 @@ RunSet.runall = function() {
       'test_bug344830.html',
       'test_bug344861.html',
       'test_bug345521.html',
+      'test_bug348497.html',
       'test_bug351601.html',
       'test_bug355026.html',
       'test_bug357509.html',
diff --git a/mozilla/testing/mochitest/tests/test_bug348497.html b/mozilla/testing/mochitest/tests/test_bug348497.html
new file mode 100644
index 00000000000..ac8467b41da
--- /dev/null
+++ b/mozilla/testing/mochitest/tests/test_bug348497.html
@@ -0,0 +1,37 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=348497
+-->
+<head>
+  <title>Test for Bug 348497</title>
+  <script type="text/javascript" src="/MochiKit/MochiKit.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>        
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=348497">Mozilla Bug 348497</a>
+<p id="display"></p>
+<div id="content">
+  This page should not crash Mozilla<br>
+  <iframe id="testIframe"></iframe>
+</div>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+/** Test for Bug 348497 **/
+function doe() {
+    document.getElementById('testIframe').style.display = 'block';
+    document.getElementById('testIframe').contentDocument.designMode = 'on';
+}
+
+SimpleTest.waitForExplicitFinish();
+addLoadEvent(doe);
+addLoadEvent(function() { ok(true, "enabling designmode on an iframe onload does not crash Mozilla")});
+addLoadEvent(SimpleTest.finish);
+
+</script>
+</pre>
+</body>
+</html>
+
