diff --git a/dom/workers/ServiceWorkerClient.cpp b/dom/workers/ServiceWorkerClient.cpp
index 13a4d9d9b8f0..f7bc5b961924 100644
--- a/dom/workers/ServiceWorkerClient.cpp
+++ b/dom/workers/ServiceWorkerClient.cpp
@@ -231,7 +231,7 @@ ServiceWorkerClient::PostMessage(JSContext* aCx, JS::Handle<JS::Value> aMessage,
     return;
   }
 
-  aRv = NS_DispatchToMainThread(runnable);
+  aRv = workerPrivate->DispatchToMainThread(runnable.forget());
   if (NS_WARN_IF(aRv.Failed())) {
     return;
   }
diff --git a/dom/workers/ServiceWorkerClients.cpp b/dom/workers/ServiceWorkerClients.cpp
index 408bbef0b798..ba8aca79a6d5 100644
--- a/dom/workers/ServiceWorkerClients.cpp
+++ b/dom/workers/ServiceWorkerClients.cpp
@@ -675,7 +675,7 @@ ServiceWorkerClients::Get(const nsAString& aClientId, ErrorResult& aRv)
 
   RefPtr<GetRunnable> r =
     new GetRunnable(promiseProxy, aClientId);
-  MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(r));
+  MOZ_ALWAYS_SUCCEEDS(workerPrivate->DispatchToMainThread(r.forget()));
   return promise.forget();
 }
 
@@ -711,7 +711,7 @@ ServiceWorkerClients::MatchAll(const ClientQueryOptions& aOptions,
     new MatchAllRunnable(promiseProxy,
                          NS_ConvertUTF16toUTF8(scope),
                          aOptions.mIncludeUncontrolled);
-  MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(r));
+  MOZ_ALWAYS_SUCCEEDS(workerPrivate->DispatchToMainThread(r.forget()));
   return promise.forget();
 }
 
@@ -752,7 +752,7 @@ ServiceWorkerClients::OpenWindow(const nsAString& aUrl,
 
   RefPtr<OpenWindowRunnable> r = new OpenWindowRunnable(promiseProxy,
                                                           aUrl, scope);
-  MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(r));
+  MOZ_ALWAYS_SUCCEEDS(workerPrivate->DispatchToMainThread(r.forget()));
 
   return promise.forget();
 }
@@ -781,6 +781,6 @@ ServiceWorkerClients::Claim(ErrorResult& aRv)
   RefPtr<ClaimRunnable> runnable =
     new ClaimRunnable(promiseProxy, NS_ConvertUTF16toUTF8(scope));
 
-  MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(runnable));
+  MOZ_ALWAYS_SUCCEEDS(workerPrivate->DispatchToMainThread(runnable.forget()));
   return promise.forget();
 }
diff --git a/dom/workers/ServiceWorkerEvents.cpp b/dom/workers/ServiceWorkerEvents.cpp
index fee9069deec1..df78bd1f57e0 100644
--- a/dom/workers/ServiceWorkerEvents.cpp
+++ b/dom/workers/ServiceWorkerEvents.cpp
@@ -394,7 +394,13 @@ void RespondWithCopyComplete(void* aClosure, nsresult aStatus)
                                data->mScriptSpec,
                                data->mResponseURLSpec);
   }
-  MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(event));
+  // In theory this can happen after the worker thread is terminated.
+  WorkerPrivate* worker = GetCurrentThreadWorkerPrivate();
+  if (worker) {
+    MOZ_ALWAYS_SUCCEEDS(worker->DispatchToMainThread(event.forget()));
+  } else {
+    MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(event.forget()));
+  }
 }
 
 namespace {
@@ -724,7 +730,13 @@ RespondWithHandler::CancelRequest(nsresult aStatus)
 {
   nsCOMPtr<nsIRunnable> runnable =
     new CancelChannelRunnable(mInterceptedChannel, mRegistration, aStatus);
-  NS_DispatchToMainThread(runnable);
+  // Note, this may run off the worker thread during worker termination.
+  WorkerPrivate* worker = GetCurrentThreadWorkerPrivate();
+  if (worker) {
+    MOZ_ALWAYS_SUCCEEDS(worker->DispatchToMainThread(runnable.forget()));
+  } else {
+    MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(runnable.forget()));
+  }
   mRequestWasHandled = true;
 }
 
@@ -857,8 +869,8 @@ public:
       mColumn = column;
     }
 
-    MOZ_ALWAYS_SUCCEEDS(
-      NS_DispatchToMainThread(NewRunnableMethod(this, &WaitUntilHandler::ReportOnMainThread)));
+    MOZ_ALWAYS_SUCCEEDS(mWorkerPrivate->DispatchToMainThread(
+        NewRunnableMethod(this, &WaitUntilHandler::ReportOnMainThread)));
   }
 
   void
diff --git a/dom/workers/ServiceWorkerPrivate.cpp b/dom/workers/ServiceWorkerPrivate.cpp
index 0682aa4c0a03..d24bc11a35b9 100644
--- a/dom/workers/ServiceWorkerPrivate.cpp
+++ b/dom/workers/ServiceWorkerPrivate.cpp
@@ -212,7 +212,7 @@ private:
     mDone = true;
 #endif
     mCallback->SetResult(aResult);
-    MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(mCallback));
+    MOZ_ALWAYS_SUCCEEDS(mWorkerPrivate->DispatchToMainThread(mCallback));
   }
 };
 
@@ -495,7 +495,7 @@ public:
   {
     nsCOMPtr<nsIRunnable> runnable =
       new RegistrationUpdateRunnable(mRegistration, true /* time check */);
-    NS_DispatchToMainThread(runnable.forget());
+    aWorkerPrivate->DispatchToMainThread(runnable.forget());
 
     ExtendableEventWorkerRunnable::PostRun(aCx, aWorkerPrivate, aRunResult);
   }
@@ -535,7 +535,7 @@ public:
   Cancel() override
   {
     mCallback->SetResult(false);
-    MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(mCallback));
+    MOZ_ALWAYS_SUCCEEDS(mWorkerPrivate->DispatchToMainThread(mCallback));
 
     return WorkerRunnable::Cancel();
   }
@@ -631,7 +631,7 @@ public:
     mDone = true;
 
     mCallback->SetResult(aResult);
-    nsresult rv = NS_DispatchToMainThread(mCallback);
+    nsresult rv = mWorkerPrivate->DispatchToMainThread(mCallback);
     if (NS_WARN_IF(NS_FAILED(rv))) {
       NS_RUNTIMEABORT("Failed to dispatch life cycle event handler.");
     }
@@ -762,6 +762,7 @@ public:
 
   void Report(uint16_t aReason = nsIPushErrorReporter::DELIVERY_INTERNAL_ERROR)
   {
+    WorkerPrivate* workerPrivate = mWorkerPrivate;
     mWorkerPrivate->AssertIsOnWorkerThread();
     mWorkerPrivate = nullptr;
 
@@ -773,7 +774,7 @@ public:
       NewRunnableMethod<uint16_t>(this,
         &PushErrorReporter::ReportOnMainThread, aReason);
     MOZ_ALWAYS_TRUE(NS_SUCCEEDED(
-      NS_DispatchToMainThread(runnable.forget())));
+      workerPrivate->DispatchToMainThread(runnable.forget())));
   }
 
   void ReportOnMainThread(uint16_t aReason)
@@ -1420,7 +1421,7 @@ public:
   Cancel() override
   {
     nsCOMPtr<nsIRunnable> runnable = new ResumeRequest(mInterceptedChannel);
-    if (NS_FAILED(NS_DispatchToMainThread(runnable))) {
+    if (NS_FAILED(mWorkerPrivate->DispatchToMainThread(runnable))) {
       NS_WARNING("Failed to resume channel on FetchEventRunnable::Cancel()!\n");
     }
     WorkerRunnable::Cancel();
@@ -1534,7 +1535,7 @@ private:
                                              NS_ERROR_INTERCEPTION_FAILED);
       }
 
-      MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(runnable));
+      MOZ_ALWAYS_SUCCEEDS(mWorkerPrivate->DispatchToMainThread(runnable.forget()));
     }
 
     RefPtr<Promise> waitUntilPromise = event->GetPromise();
diff --git a/dom/workers/ServiceWorkerRegistration.cpp b/dom/workers/ServiceWorkerRegistration.cpp
index 1f619c42cf73..9c9d2b57162f 100644
--- a/dom/workers/ServiceWorkerRegistration.cpp
+++ b/dom/workers/ServiceWorkerRegistration.cpp
@@ -1110,7 +1110,7 @@ ServiceWorkerRegistrationWorkerThread::Update(ErrorResult& aRv)
   }
 
   RefPtr<UpdateRunnable> r = new UpdateRunnable(proxy, mScope);
-  MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(r));
+  MOZ_ALWAYS_SUCCEEDS(worker->DispatchToMainThread(r.forget()));
 
   return promise.forget();
 }
@@ -1142,7 +1142,7 @@ ServiceWorkerRegistrationWorkerThread::Unregister(ErrorResult& aRv)
   }
 
   RefPtr<StartUnregisterRunnable> r = new StartUnregisterRunnable(proxy, mScope);
-  MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(r));
+  MOZ_ALWAYS_SUCCEEDS(worker->DispatchToMainThread(r.forget()));
 
   return promise.forget();
 }
@@ -1180,7 +1180,7 @@ ServiceWorkerRegistrationWorkerThread::InitListener()
 
   RefPtr<StartListeningRunnable> r =
     new StartListeningRunnable(mListener);
-  MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(r));
+  MOZ_ALWAYS_SUCCEEDS(worker->DispatchToMainThread(r.forget()));
 }
 
 class AsyncStopListeningRunnable final : public Runnable
@@ -1238,7 +1238,7 @@ ServiceWorkerRegistrationWorkerThread::ReleaseListener(Reason aReason)
   if (aReason == RegistrationIsGoingAway) {
     RefPtr<AsyncStopListeningRunnable> r =
       new AsyncStopListeningRunnable(mListener);
-    MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(r));
+    MOZ_ALWAYS_SUCCEEDS(mWorkerPrivate->DispatchToMainThread(r.forget()));
   } else if (aReason == WorkerIsGoingAway) {
     RefPtr<SyncStopListeningRunnable> r =
       new SyncStopListeningRunnable(mWorkerPrivate, mListener);
diff --git a/dom/workers/ServiceWorkerWindowClient.cpp b/dom/workers/ServiceWorkerWindowClient.cpp
index 9dd42ee0415f..7cc1eb6c5688 100644
--- a/dom/workers/ServiceWorkerWindowClient.cpp
+++ b/dom/workers/ServiceWorkerWindowClient.cpp
@@ -183,7 +183,7 @@ ServiceWorkerWindowClient::Focus(ErrorResult& aRv) const
     if (promiseProxy) {
       RefPtr<ClientFocusRunnable> r = new ClientFocusRunnable(mWindowId,
                                                               promiseProxy);
-      MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(r));
+      MOZ_ALWAYS_SUCCEEDS(workerPrivate->DispatchToMainThread(r.forget()));
     } else {
       promise->MaybeReject(NS_ERROR_DOM_ABORT_ERR);
     }
@@ -516,7 +516,7 @@ ServiceWorkerWindowClient::Navigate(const nsAString& aUrl, ErrorResult& aRv)
   if (promiseProxy) {
     RefPtr<ClientNavigateRunnable> r =
       new ClientNavigateRunnable(mWindowId, aUrl, promiseProxy);
-    MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(r));
+    MOZ_ALWAYS_SUCCEEDS(workerPrivate->DispatchToMainThread(r.forget()));
   } else {
     promise->MaybeReject(NS_ERROR_DOM_ABORT_ERR);
   }
diff --git a/dom/workers/WorkerScope.cpp b/dom/workers/WorkerScope.cpp
index 480fddc8d58b..332b2687255a 100644
--- a/dom/workers/WorkerScope.cpp
+++ b/dom/workers/WorkerScope.cpp
@@ -697,7 +697,7 @@ ServiceWorkerGlobalScope::SkipWaiting(ErrorResult& aRv)
     new WorkerScopeSkipWaitingRunnable(promiseProxy,
                                        NS_ConvertUTF16toUTF8(mScope));
 
-  MOZ_ALWAYS_SUCCEEDS(NS_DispatchToMainThread(runnable));
+  MOZ_ALWAYS_SUCCEEDS(mWorkerPrivate->DispatchToMainThread(runnable.forget()));
   return promise.forget();
 }