diff --git a/js/src/jsapi.cpp b/js/src/jsapi.cpp
index 300b4b69c177..d9fe319a9f55 100644
--- a/js/src/jsapi.cpp
+++ b/js/src/jsapi.cpp
@@ -1480,7 +1480,8 @@ JS_EnumerateStandardClasses(JSContext *cx, JSObject *obj)
     atom = rt->atomState.typeAtoms[JSTYPE_VOID];
     if (!AlreadyHasOwnProperty(cx, obj, atom) &&
         !obj->defineProperty(cx, ATOM_TO_JSID(atom), JSVAL_VOID,
-                             JS_PropertyStub, JS_PropertyStub, JSPROP_PERMANENT)) {
+                             JS_PropertyStub, JS_PropertyStub,
+                             JSPROP_PERMANENT | JSPROP_READONLY)) {
         return JS_FALSE;
     }
 
diff --git a/js/src/tests/ecma_5/misc/enumerate-undefined.js b/js/src/tests/ecma_5/misc/enumerate-undefined.js
new file mode 100644
index 000000000000..163c611b2025
--- /dev/null
+++ b/js/src/tests/ecma_5/misc/enumerate-undefined.js
@@ -0,0 +1,25 @@
+/*
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/
+ */
+
+var gTestfile = 'enumerate-undefined.js';
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 547087;
+var summary = 'JS_EnumerateStandardClasses uses wrong attributes for undefined';
+
+print(BUGNUMBER + ": " + summary);
+
+/**************
+ * BEGIN TEST *
+ **************/
+
+for (var p in this);
+
+assertEq(Object.getOwnPropertyDescriptor(this, "undefined").writable, false);
+
+/******************************************************************************/
+
+reportCompare(true, true);
+
+print("All tests passed!");
diff --git a/js/src/tests/ecma_5/misc/jstests.list b/js/src/tests/ecma_5/misc/jstests.list
index 3a1e67a12100..136f00db5816 100644
--- a/js/src/tests/ecma_5/misc/jstests.list
+++ b/js/src/tests/ecma_5/misc/jstests.list
@@ -1,3 +1,4 @@
 url-prefix ../../jsreftest.html?test=ecma_5/misc/
 script global-numeric-properties.js
 script redeclare-var-non-writable-property.js
+script enumerate-undefined.js