diff --git a/editor/libeditor/text/tests/Makefile.in b/editor/libeditor/text/tests/Makefile.in
index 9730312f98c..5b39ebfb402 100644
--- a/editor/libeditor/text/tests/Makefile.in
+++ b/editor/libeditor/text/tests/Makefile.in
@@ -59,6 +59,7 @@ _TEST_FILES = \
 		test_bug604532.html \
 		test_bug625452.html \
 		test_bug629172.html \
+		test_bug638596.html \
 		test_bug641466.html \
 		$(NULL)
 
diff --git a/editor/libeditor/text/tests/test_bug638596.html b/editor/libeditor/text/tests/test_bug638596.html
new file mode 100644
index 00000000000..50bce4d1523
--- /dev/null
+++ b/editor/libeditor/text/tests/test_bug638596.html
@@ -0,0 +1,38 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=638596
+-->
+<head>
+  <title>Test for Bug 638596</title>
+  <script type="application/javascript" src="/MochiKit/packed.js"></script>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/EventUtils.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=638596">Mozilla Bug 638596</a>
+<p id="display"></p>
+<div id="content">
+  <input type="password" style="font-size: 0">
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 638596 **/
+SimpleTest.waitForExplicitFinish();
+SimpleTest.waitForFocus(function() {
+  var i = document.querySelector("input");
+  i.focus();
+  synthesizeKey("t", {});
+  synthesizeKey("e", {});
+  synthesizeKey("s", {});
+  synthesizeKey("t", {});
+  is(i.value, "test", "The correct value should be stored in the field");
+  SimpleTest.finish();
+});
+
+</script>
+</pre>
+</body>
+</html>
