diff --git a/mozilla/layout/generic/crashtests/366021-1.xhtml b/mozilla/layout/generic/crashtests/366021-1.xhtml
new file mode 100644
index 00000000000..5bbc7fe185c
--- /dev/null
+++ b/mozilla/layout/generic/crashtests/366021-1.xhtml
@@ -0,0 +1,24 @@
+<html xmlns="http://www.w3.org/1999/xhtml" class="reftest-wait">
+
+<head>
+<script>
+
+function boom()
+{
+  document.getElementById("xulwin").appendChild(document.getElementById("sss"));
+  document.documentElement.removeAttribute("class");
+}
+
+</script>
+</head>
+
+
+<body onload="setTimeout(boom, 10)">
+
+<span id="sss"><tr><td style="position: absolute;">td</td></tr></span>
+
+<window id="xulwin" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"></window>
+
+</body>
+
+</html>
diff --git a/mozilla/layout/generic/crashtests/crashtests.list b/mozilla/layout/generic/crashtests/crashtests.list
index 0159b716c3a..7c0ec99189e 100644
--- a/mozilla/layout/generic/crashtests/crashtests.list
+++ b/mozilla/layout/generic/crashtests/crashtests.list
@@ -27,6 +27,7 @@ load 359371-2.html
 load 363848-1.xhtml
 load 364407-1.html
 load 364686-1.xhtml
+load 366021-1.xhtml
 load 366667-1.html
 load 366952-1.html
 load 368330-1.html
