diff --git a/dom/workers/Worker.cpp b/dom/workers/Worker.cpp
index 41029178db7..c1d100c0de2 100644
--- a/dom/workers/Worker.cpp
+++ b/dom/workers/Worker.cpp
@@ -91,8 +91,8 @@ public:
   InitClass(JSContext* aCx, JSObject* aObj, JSObject* aParentProto,
             bool aMainRuntime)
   {
-    JSObject* proto = JS_InitClass(aCx, aObj, aParentProto, &sClass, Construct,
-                                   0, sProperties, sFunctions, NULL, NULL);
+    JSObject* proto = js::InitClassWithReserved(aCx, aObj, aParentProto, &sClass, Construct,
+                                                0, sProperties, sFunctions, NULL, NULL);
     if (!proto) {
       return NULL;
     }
@@ -102,11 +102,10 @@ public:
       parent->AssertIsOnWorkerThread();
 
       JSObject* constructor = JS_GetConstructor(aCx, proto);
-      if (!constructor ||
-          !JS_SetReservedSlot(aCx, constructor, CONSTRUCTOR_SLOT_PARENT,
-                              PRIVATE_TO_JSVAL(parent))) {
+      if (!constructor)
         return NULL;
-      }
+      js::SetFunctionNativeReserved(constructor, CONSTRUCTOR_SLOT_PARENT,
+                                    PRIVATE_TO_JSVAL(parent));
     }
 
     return proto;
@@ -153,11 +152,8 @@ protected:
       return false;
     }
 
-    jsval priv;
-    if (!JS_GetReservedSlot(aCx, JSVAL_TO_OBJECT(JS_CALLEE(aCx, aVp)),
-                            CONSTRUCTOR_SLOT_PARENT, &priv)) {
-      return false;
-    }
+    jsval priv = js::GetFunctionNativeReserved(JSVAL_TO_OBJECT(JS_CALLEE(aCx, aVp)),
+                                               CONSTRUCTOR_SLOT_PARENT);
 
     RuntimeService* runtimeService;
     WorkerPrivate* parent;
@@ -339,8 +335,8 @@ public:
   InitClass(JSContext* aCx, JSObject* aObj, JSObject* aParentProto,
             bool aMainRuntime)
   {
-    JSObject* proto = JS_InitClass(aCx, aObj, aParentProto, &sClass, Construct,
-                                   0, NULL, NULL, NULL, NULL);
+    JSObject* proto = js::InitClassWithReserved(aCx, aObj, aParentProto, &sClass, Construct,
+                                                0, NULL, NULL, NULL, NULL);
     if (!proto) {
       return NULL;
     }
@@ -350,11 +346,10 @@ public:
       parent->AssertIsOnWorkerThread();
 
       JSObject* constructor = JS_GetConstructor(aCx, proto);
-      if (!constructor ||
-          !JS_SetReservedSlot(aCx, constructor, CONSTRUCTOR_SLOT_PARENT,
-                              PRIVATE_TO_JSVAL(parent))) {
+      if (!constructor)
         return NULL;
-      }
+      js::SetFunctionNativeReserved(constructor, CONSTRUCTOR_SLOT_PARENT,
+                                    PRIVATE_TO_JSVAL(parent));
     }
 
     return proto;