diff --git a/js/src/jscompartment.cpp b/js/src/jscompartment.cpp
index b8a8ae90439a..2076c2b7b619 100644
--- a/js/src/jscompartment.cpp
+++ b/js/src/jscompartment.cpp
@@ -45,6 +45,7 @@
 #include "jsproxy.h"
 #include "jsscope.h"
 #include "jstracer.h"
+#include "jswrapper.h"
 #include "assembler/wtf/Platform.h"
 #include "methodjit/MethodJIT.h"
 #include "methodjit/PolyIC.h"
@@ -176,6 +177,12 @@ JSCompartment::arenaListsAreEmpty()
   return true;
 }
 
+static bool
+IsCrossCompartmentWrapper(JSObject *wrapper)
+{
+    return !!(JSWrapper::wrapperHandler(wrapper)->flags() & JSWrapper::CROSS_COMPARTMENT);
+}
+
 bool
 JSCompartment::wrap(JSContext *cx, Value *vp)
 {
@@ -276,8 +283,16 @@ JSCompartment::wrap(JSContext *cx, Value *vp)
     /* If we already have a wrapper for this value, use it. */
     if (WrapperMap::Ptr p = crossCompartmentWrappers.lookup(*vp)) {
         *vp = p->value;
-        if (vp->isObject())
-            vp->toObject().setParent(global);
+        if (vp->isObject()) {
+            JSObject *obj = &vp->toObject();
+            JS_ASSERT(IsCrossCompartmentWrapper(obj));
+            if (obj->getParent() != global) {
+                do {
+                    obj->setParent(global);
+                    obj = obj->getProto();
+                } while (obj && IsCrossCompartmentWrapper(obj));
+            }
+        }
         return true;
     }
 
diff --git a/js/src/jswrapper.cpp b/js/src/jswrapper.cpp
index eea30a8c2b39..8e4e0c875790 100644
--- a/js/src/jswrapper.cpp
+++ b/js/src/jswrapper.cpp
@@ -417,12 +417,6 @@ JSCrossCompartmentWrapper::~JSCrossCompartmentWrapper()
 {
 }
 
-bool
-JSCrossCompartmentWrapper::isCrossCompartmentWrapper(JSObject *obj)
-{
-    return obj->isProxy() && obj->getProxyHandler() == &JSCrossCompartmentWrapper::singleton;
-}
-
 #define PIERCE(cx, wrapper, mode, pre, op, post)            \
     JS_BEGIN_MACRO                                          \
         AutoCompartment call(cx, wrappedObject(wrapper));   \
diff --git a/js/src/jswrapper.h b/js/src/jswrapper.h
index 86dee77a8f45..23514ff0a50e 100644
--- a/js/src/jswrapper.h
+++ b/js/src/jswrapper.h
@@ -151,8 +151,6 @@ class JS_FRIEND_API(JSCrossCompartmentWrapper) : public JSWrapper {
     virtual JSString *obj_toString(JSContext *cx, JSObject *wrapper);
     virtual JSString *fun_toString(JSContext *cx, JSObject *wrapper, uintN indent);
 
-    static bool isCrossCompartmentWrapper(JSObject *obj);
-
     static JSCrossCompartmentWrapper singleton;
 };
 
diff --git a/js/src/shell/js.cpp b/js/src/shell/js.cpp
index a159cdac4431..9605ba770829 100644
--- a/js/src/shell/js.cpp
+++ b/js/src/shell/js.cpp
@@ -3459,8 +3459,10 @@ EvalInContext(JSContext *cx, uintN argc, jsval *vp)
     JSStackFrame *fp = JS_GetScriptedCaller(cx, NULL);
     {
         JSAutoEnterCompartment ac;
-        if (JSCrossCompartmentWrapper::isCrossCompartmentWrapper(sobj)) {
-            sobj = sobj->unwrap();
+        uintN flags;
+        JSObject *unwrapped = sobj->unwrap(&flags);
+        if (flags & JSWrapper::CROSS_COMPARTMENT) {
+            sobj = unwrapped;
             if (!ac.enter(cx, sobj))
                 return false;
         }