diff --git a/js/xpconnect/src/XPCMaps.h b/js/xpconnect/src/XPCMaps.h
index 0cc7c358eaea..77bb18f3f947 100644
--- a/js/xpconnect/src/XPCMaps.h
+++ b/js/xpconnect/src/XPCMaps.h
@@ -646,7 +646,7 @@ public:
             return p->value;
         if (!mTable.add(p, key, value))
             return nullptr;
-        MOZ_ASSERT(xpc::GetCompartmentPrivate(key)->scope->mWaiverWrapperMap == this);
+        MOZ_ASSERT(xpc::GetObjectScope(key)->mWaiverWrapperMap == this);
         JS_StoreObjectPostBarrierCallback(cx, KeyMarkCallback, key, this);
         return value;
     }