diff --git a/layout/base/tests/Makefile.in b/layout/base/tests/Makefile.in
index 0c1bc6de4857..b533e7dde228 100644
--- a/layout/base/tests/Makefile.in
+++ b/layout/base/tests/Makefile.in
@@ -83,6 +83,7 @@ ifdef MOZ_MOCHITEST
 _TEST_FILES =	\
 		test_bug66619.html \
 		test_bug388019.html \
+		test_bug399951.html \
 		$(NULL)
 
 libs:: $(_TEST_FILES)
diff --git a/layout/base/tests/test_bug399951.html b/layout/base/tests/test_bug399951.html
new file mode 100755
index 000000000000..20574189433f
--- /dev/null
+++ b/layout/base/tests/test_bug399951.html
@@ -0,0 +1,34 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=399951
+-->
+<head>
+  <title>Test for Bug 399951</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 style="direction: rtl" onload="document.body.style.direction = 'ltr';">
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=399951">Mozilla Bug 399951</a>
+<div style="white-space: pre;">
+.i
+  h
+  f
+</div>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+ function test()
+{
+/** Test for Bug 399951 **/
+  ok(true, "Should not crash");
+  SimpleTest.finish();
+}
+
+  setTimeout(test, 500);
+  SimpleTest.waitForExplicitFinish();
+</script>
+</pre>
+</body>
+</html>
+
