diff --git a/mozilla/layout/base/crashtests/401589-1.xul b/mozilla/layout/base/crashtests/401589-1.xul
new file mode 100644
index 00000000000..5d815c2cb0d
--- /dev/null
+++ b/mozilla/layout/base/crashtests/401589-1.xul
@@ -0,0 +1,29 @@
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        xmlns:html="http://www.w3.org/1999/xhtml"
+        xmlns:math="http://www.w3.org/1998/Math/MathML"
+        class="reftest-wait"
+        onload="boom();">
+        
+<html:style type="text/css">
+[class="mp"] { display: -moz-popup; }
+</html:style>
+
+<script>
+
+function boom()
+{
+  document.getElementById("mtd").setAttribute("class", "mp");
+  setTimeout(boom2, 30);
+}
+
+function boom2()
+{
+  document.getElementById("mtd").setAttribute("class", "");
+  document.documentElement.removeAttribute("class");
+}
+
+</script>
+
+<math:mtd id="mtd" />
+
+</window>
diff --git a/mozilla/layout/base/crashtests/crashtests.list b/mozilla/layout/base/crashtests/crashtests.list
index dc6ef50d1a3..f587075394a 100644
--- a/mozilla/layout/base/crashtests/crashtests.list
+++ b/mozilla/layout/base/crashtests/crashtests.list
@@ -62,6 +62,7 @@ load 399940-1.xhtml
 load 399946-1.xhtml
 load 400445-1.xhtml
 load 400904-1.xhtml
+load 401589-1.xul
 load 403175-1.html
 load 403245-1.html
 load 403569-1.xhtml