diff --git a/dom/media/MediaManager.cpp b/dom/media/MediaManager.cpp
index ad09d97a8743..661d73d1f078 100644
--- a/dom/media/MediaManager.cpp
+++ b/dom/media/MediaManager.cpp
@@ -148,7 +148,7 @@ using media::NewTaskFrom;
 using media::Pledge;
 using media::Refcountable;
 
-static Atomic<bool> sInShutdown;
+static Atomic<bool> sHasShutdown;
 
 typedef media::Pledge<bool, dom::MediaStreamError*> PledgeVoid;
 
@@ -1095,7 +1095,7 @@ public:
                          const MediaTrackConstraints& aConstraints,
                          dom::CallerType aCallerType) override
         {
-          if (sInShutdown || !mListener) {
+          if (sHasShutdown || !mListener) {
             // Track has been stopped, or we are in shutdown. In either case
             // there's no observable outcome, so pretend we succeeded.
             RefPtr<PledgeVoid> p = new PledgeVoid();
@@ -1176,14 +1176,14 @@ public:
       }
     }
 
-    if (!domStream || !stream || sInShutdown) {
+    if (!domStream || !stream || sHasShutdown) {
       nsCOMPtr<nsIDOMGetUserMediaErrorCallback> onFailure = mOnFailure.forget();
       LOG(("Returning error for getUserMedia() - no stream"));
 
       if (auto* window = nsGlobalWindowInner::GetInnerWindowWithId(mWindowID)) {
         RefPtr<MediaStreamError> error = new MediaStreamError(window->AsInner(),
             NS_LITERAL_STRING("InternalError"),
-            sInShutdown ? NS_LITERAL_STRING("In shutdown") :
+            sHasShutdown ? NS_LITERAL_STRING("In shutdown") :
                           NS_LITERAL_STRING("No stream."));
         onFailure->OnError(error);
       }
@@ -1978,7 +1978,7 @@ MediaManager::StartupInit()
 void
 MediaManager::PostTask(already_AddRefed<Runnable> task)
 {
-  if (sInShutdown) {
+  if (sHasShutdown) {
     // Can't safely delete task here since it may have items with specific
     // thread-release requirements.
     // XXXkhuey well then who is supposed to delete it?! We don't signal
@@ -2055,7 +2055,7 @@ void MediaManager::OnDeviceChange() {
   RefPtr<MediaManager> self(this);
   NS_DispatchToMainThread(media::NewRunnableFrom([self]() mutable {
     MOZ_ASSERT(NS_IsMainThread());
-    if (sInShutdown) {
+    if (sHasShutdown) {
       return NS_OK;
     }
     self->DeviceChangeCallback::OnDeviceChange();
@@ -2218,7 +2218,7 @@ MediaManager::GetUserMedia(nsPIDOMWindowInner* aWindow,
     return NS_OK;
   }
 
-  if (sInShutdown) {
+  if (sHasShutdown) {
     RefPtr<MediaStreamError> error =
         new MediaStreamError(aWindow,
                              NS_LITERAL_STRING("AbortError"),
@@ -2816,7 +2816,7 @@ MediaManager::EnumerateDevices(nsPIDOMWindowInner* aWindow,
                                dom::CallerType aCallerType)
 {
   MOZ_ASSERT(NS_IsMainThread());
-  NS_ENSURE_TRUE(!sInShutdown, NS_ERROR_FAILURE);
+  NS_ENSURE_TRUE(!sHasShutdown, NS_ERROR_FAILURE);
   nsCOMPtr<nsIGetUserMediaDevicesSuccessCallback> onSuccess(aOnSuccess);
   nsCOMPtr<nsIDOMGetUserMediaErrorCallback> onFailure(aOnFailure);
   uint64_t windowId = aWindow->WindowID();
@@ -2908,7 +2908,7 @@ MediaManager::GetBackend(uint64_t aWindowId)
   // includes picture support for Android.
   // This IS called off main-thread.
   if (!mBackend) {
-    MOZ_RELEASE_ASSERT(!sInShutdown);  // we should never create a new backend in shutdown
+    MOZ_RELEASE_ASSERT(!sHasShutdown);  // we should never create a new backend in shutdown
 #if defined(MOZ_WEBRTC)
     mBackend = new MediaEngineWebRTC(mPrefs);
 #else
@@ -3086,10 +3086,9 @@ void
 MediaManager::Shutdown()
 {
   MOZ_ASSERT(NS_IsMainThread());
-  if (sInShutdown) {
+  if (sHasShutdown) {
     return;
   }
-  sInShutdown = true;
 
   nsCOMPtr<nsIObserverService> obs = services::GetObserverService();
 
@@ -3128,6 +3127,10 @@ MediaManager::Shutdown()
   StopWebRtcLog();
 #endif
 
+  // From main thread's point of view, shutdown is now done.
+  // All that remains is shutting down the media thread.
+  sHasShutdown = true;
+
   // Because mMediaThread is not an nsThread, we must dispatch to it so it can
   // clean up BackgroundChild. Continue stopping thread once this is done.
 
@@ -3180,7 +3183,7 @@ MediaManager::Shutdown()
   RefPtr<MediaManager> that = this;
 
   // Release the backend (and call Shutdown()) from within the MediaManager thread
-  // Don't use MediaManager::PostTask() because we're sInShutdown=true here!
+  // Don't use MediaManager::PostTask() because we're sHasShutdown=true here!
   RefPtr<ShutdownTask> shutdown = new ShutdownTask(this,
       media::NewRunnableFrom([this, that]() mutable {
     LOG(("MediaManager shutdown lambda running, releasing MediaManager singleton and thread"));
@@ -3291,7 +3294,7 @@ MediaManager::Observe(nsISupports* aSubject, const char* aTopic,
       }
     }
 
-    if (sInShutdown) {
+    if (sHasShutdown) {
       return task->Denied(NS_LITERAL_STRING("In shutdown"));
     }
     // Reuse the same thread to save memory.