diff --git a/js/src/jscntxt.h b/js/src/jscntxt.h
index d0b654bacab..141ee25690e 100644
--- a/js/src/jscntxt.h
+++ b/js/src/jscntxt.h
@@ -1710,16 +1710,21 @@ class AutoGCRooter {
     void operator=(AutoGCRooter &ida);
 };
 
-class AutoSaveWeakRoots : private AutoGCRooter
+class AutoSaveRestoreWeakRoots : private AutoGCRooter
 {
   public:
-    explicit AutoSaveWeakRoots(JSContext *cx
-                               JS_GUARD_OBJECT_NOTIFIER_PARAM)
+    explicit AutoSaveRestoreWeakRoots(JSContext *cx
+                                      JS_GUARD_OBJECT_NOTIFIER_PARAM)
       : AutoGCRooter(cx, WEAKROOTS), savedRoots(cx->weakRoots)
     {
         JS_GUARD_OBJECT_NOTIFIER_INIT;
     }
 
+    ~AutoSaveRestoreWeakRoots()
+    {
+        context->weakRoots = savedRoots;
+    }
+
     friend void AutoGCRooter::trace(JSTracer *trc);
 
   private:
diff --git a/js/src/jscntxtinlines.h b/js/src/jscntxtinlines.h
index ff633e08c5b..1b92509e884 100644
--- a/js/src/jscntxtinlines.h
+++ b/js/src/jscntxtinlines.h
@@ -78,7 +78,7 @@ AutoGCRooter::trace(JSTracer *trc)
         return;
 
       case WEAKROOTS:
-        static_cast<AutoSaveWeakRoots *>(this)->savedRoots.mark(trc);
+        static_cast<AutoSaveRestoreWeakRoots *>(this)->savedRoots.mark(trc);
         return;
 
       case PARSER:
diff --git a/js/src/jsgc.cpp b/js/src/jsgc.cpp
index f0ae73e35eb..98c6e5af80e 100644
--- a/js/src/jsgc.cpp
+++ b/js/src/jsgc.cpp
@@ -1408,7 +1408,7 @@ LastDitchGC(JSContext *cx)
     JS_ASSERT(!JS_ON_TRACE(cx));
 
     /* The last ditch GC preserves weak roots and all atoms. */
-    AutoSaveWeakRoots save(cx);
+    AutoSaveRestoreWeakRoots save(cx);
     AutoKeepAtoms keep(cx->runtime);
 
     /*