diff --git a/source/scriptinterface/Promises.cpp b/source/scriptinterface/Promises.cpp
index a871bc5c39..e8504d8c42 100644
--- a/source/scriptinterface/Promises.cpp
+++ b/source/scriptinterface/Promises.cpp
@@ -85,7 +85,7 @@ bool JobQueue::empty() const
 
 js::UniquePtr<JS::JobQueue::SavedJobQueue> JobQueue::saveJobQueue(JSContext*)
 {
-	class SavedJobQueue : public JS::JobQueue::SavedJobQueue
+	class SavedJobQueue final : public JS::JobQueue::SavedJobQueue
 	{
 	public:
 		SavedJobQueue(QueueType& queue) :
diff --git a/source/scriptinterface/Promises.h b/source/scriptinterface/Promises.h
index 6e64da5d54..4ee2cfe9c8 100644
--- a/source/scriptinterface/Promises.h
+++ b/source/scriptinterface/Promises.h
@@ -35,7 +35,7 @@ namespace Script
 void UnhandledRejectedPromise(JSContext* cx, bool, JS::HandleObject promise,
 	JS::PromiseRejectionHandlingState state, void*);
 
-class JobQueue : public JS::JobQueue
+class JobQueue final : public JS::JobQueue
 {
 public:
 	~JobQueue() final = default;