diff --git a/dom/workers/ServiceWorkerEvents.cpp b/dom/workers/ServiceWorkerEvents.cpp
index d7bdcb550f14..96cb7d7639e9 100644
--- a/dom/workers/ServiceWorkerEvents.cpp
+++ b/dom/workers/ServiceWorkerEvents.cpp
@@ -59,9 +59,9 @@ CancelChannelRunnable::Run()
 }
 
 FetchEvent::FetchEvent(EventTarget* aOwner)
-: ExtendableEvent(aOwner)
-, mIsReload(false)
-, mWaitToRespond(false)
+  : ExtendableEvent(aOwner)
+  , mIsReload(false)
+  , mWaitToRespond(false)
 {
 }
 
@@ -436,15 +436,6 @@ FetchEvent::RespondWith(Promise& aArg, ErrorResult& aRv)
     return;
   }
 
-  // 4.5.3.2 If the respond-with entered flag is set, then:
-  // Throw an "InvalidStateError" exception.
-  // Here we use |mPromise != nullptr| as respond-with enter flag
-  if (mPromise) {
-    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
-    return;
-  }
-  mPromise = &aArg;
-
   RefPtr<InternalRequest> ir = mRequest->GetInternalRequest();
   StopImmediatePropagation();
   mWaitToRespond = true;
@@ -452,6 +443,8 @@ FetchEvent::RespondWith(Promise& aArg, ErrorResult& aRv)
     new RespondWithHandler(mChannel, mRequest->Mode(), ir->IsClientRequest(),
                            ir->IsNavigationRequest(), mScriptSpec);
   aArg.AppendNativeHandler(handler);
+
+  WaitUntil(aArg, aRv);
 }
 
 NS_IMPL_ADDREF_INHERITED(FetchEvent, ExtendableEvent)
@@ -460,8 +453,7 @@ NS_IMPL_RELEASE_INHERITED(FetchEvent, ExtendableEvent)
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(FetchEvent)
 NS_INTERFACE_MAP_END_INHERITING(ExtendableEvent)
 
-NS_IMPL_CYCLE_COLLECTION_INHERITED(FetchEvent, ExtendableEvent,
-                                   mRequest, mPromise)
+NS_IMPL_CYCLE_COLLECTION_INHERITED(FetchEvent, ExtendableEvent, mRequest)
 
 ExtendableEvent::ExtendableEvent(EventTarget* aOwner)
   : Event(aOwner, nullptr, nullptr)
diff --git a/dom/workers/ServiceWorkerEvents.h b/dom/workers/ServiceWorkerEvents.h
index 1e095b8ff8ad..0e852fb30bcb 100644
--- a/dom/workers/ServiceWorkerEvents.h
+++ b/dom/workers/ServiceWorkerEvents.h
@@ -103,7 +103,6 @@ class FetchEvent final : public ExtendableEvent
   nsMainThreadPtrHandle<nsIInterceptedChannel> mChannel;
   RefPtr<Request> mRequest;
   nsCString mScriptSpec;
-  RefPtr<Promise> mPromise;
   bool mIsReload;
   bool mWaitToRespond;
 protected:
@@ -150,13 +149,6 @@ public:
   void
   RespondWith(Promise& aArg, ErrorResult& aRv);
 
-  already_AddRefed<Promise>
-  GetPromise() const
-  {
-    RefPtr<Promise> p = mPromise;
-    return p.forget();
-  }
-
   already_AddRefed<Promise>
   ForwardTo(const nsAString& aUrl);
 
diff --git a/dom/workers/ServiceWorkerPrivate.cpp b/dom/workers/ServiceWorkerPrivate.cpp
index 11504551fd1c..038d3d271c9f 100644
--- a/dom/workers/ServiceWorkerPrivate.cpp
+++ b/dom/workers/ServiceWorkerPrivate.cpp
@@ -1175,11 +1175,11 @@ private:
       MOZ_ALWAYS_TRUE(NS_SUCCEEDED(NS_DispatchToMainThread(runnable)));
     }
 
-    RefPtr<Promise> respondWithPromise = event->GetPromise();
-    if (respondWithPromise) {
+    RefPtr<Promise> waitUntilPromise = event->GetPromise();
+    if (waitUntilPromise) {
       RefPtr<KeepAliveHandler> keepAliveHandler =
         new KeepAliveHandler(mKeepAliveToken);
-      respondWithPromise->AppendNativeHandler(keepAliveHandler);
+      waitUntilPromise->AppendNativeHandler(keepAliveHandler);
     }
 
     // 9.8.22 If request is a non-subresource request, then: Invoke Soft Update algorithm