diff --git a/testing/mochitest/tests/index.html b/testing/mochitest/tests/index.html
index b88cbfb90f4..6569f9fbec2 100644
--- a/testing/mochitest/tests/index.html
+++ b/testing/mochitest/tests/index.html
@@ -66,6 +66,7 @@ RunSet.runall = function() {
       'test_bug238409.html',
       'test_bug277724.html',
       'test_bug302186.html',
+      'test_bug308484.html',
       'test_bug308856.html',
       'test_bug333983.html',
       'test_bug337124.html',
diff --git a/testing/mochitest/tests/test_bug308484.html b/testing/mochitest/tests/test_bug308484.html
new file mode 100644
index 00000000000..014a570cc36
--- /dev/null
+++ b/testing/mochitest/tests/test_bug308484.html
@@ -0,0 +1,61 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=308484
+-->
+<head>
+  <title>Test for Bug 308484</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=308484">Mozilla Bug 308484</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+  
+</div>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+
+/** Test for Bug 308484 **/
+
+var headers = ["Host", "Content-Length", "Transfer-Encoding", "Via", "Upgrade"];
+var i, request;
+
+// Try setting headers in unprivileged context
+request = new XMLHttpRequest();
+request.open("GET", window.location.href);
+for (i = 0; i < headers.length; i++)
+  request.setRequestHeader(headers[i], "test" + i);
+
+// Read out headers
+netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect UniversalBrowserWrite");
+var channel = request.channel.QueryInterface(Components.interfaces.nsIHttpChannel);
+for (i = 0; i < headers.length; i++) {
+  // Retrieving Content-Length will throw an exception
+  var value = null;
+  try {
+    value = channel.getRequestHeader(headers[i]);
+  }
+  catch(e) {}
+
+  isnot(value, "test" + i, "Setting " + headers[i] + " header in unprivileged context");
+}
+
+// Try setting headers in privileged context
+request = new XMLHttpRequest();
+request.open("GET", window.location.href);
+for (i = 0; i < headers.length; i++)
+  request.setRequestHeader(headers[i], "test" + i);
+
+// Read out headers
+var channel = request.channel.QueryInterface(Components.interfaces.nsIHttpChannel);
+for (i = 0; i < headers.length; i++) {
+  var value = channel.getRequestHeader(headers[i]);
+  is(value, "test" + i, "Setting " + headers[i] + " header in privileged context");
+}
+</script>
+</pre>
+</body>
+</html>
