--- a/dom/media/MediaDecoderStateMachine.cpp
+++ b/dom/media/MediaDecoderStateMachine.cpp
@@ -290,24 +290,23 @@ protected:
     -> decltype(ReturnTypeHelper(&S::Enter))
   {
     // keep mMaster in a local object because mMaster will become invalid after
     // the current state object is deleted.
     auto master = mMaster;
 
     auto s = new S(master);
 
-    MOZ_ASSERT(master->mState != s->GetState() ||
-               master->mState == DECODER_STATE_SEEKING);
+    MOZ_ASSERT(GetState() != s->GetState() ||
+               GetState() == DECODER_STATE_SEEKING);
 
     SLOG("change state to: %s", ToStateStr(s->GetState()));
 
     Exit();
 
-    master->mState = s->GetState();
     master->mStateObj.reset(s);
     return s->Enter(Move(aArgs)...);
   }
 
   RefPtr<MediaDecoder::SeekPromise>
   SetSeekingState(SeekJob&& aSeekJob, EventVisibility aVisibility);
 
   // Take a raw pointer in order not to change the life cycle of MDSM.
@@ -2734,17 +2733,16 @@ nsresult MediaDecoderStateMachine::Init(
     &MediaDecoderStateMachine::OnCDMProxyNotReady)
   ->Track(mCDMProxyPromise);
 
   nsresult rv = mReader->Init();
   NS_ENSURE_SUCCESS(rv, rv);
 
   RefPtr<MediaDecoderStateMachine> self = this;
   OwnerThread()->Dispatch(NS_NewRunnableFunction([self] () {
-    MOZ_ASSERT(self->mState == DECODER_STATE_DECODING_METADATA);
     MOZ_ASSERT(!self->mStateObj);
     auto s = new DecodeMetadataState(self);
     self->mStateObj.reset(s);
     s->Enter();
   }));
 
   return NS_OK;
 }
@@ -2830,17 +2828,17 @@ MediaDecoderStateMachine::ToStateStr(Sta
   }
   return "UNKNOWN";
 }
 
 const char*
 MediaDecoderStateMachine::ToStateStr()
 {
   MOZ_ASSERT(OnTaskQueue());
-  return ToStateStr(mState);
+  return ToStateStr(mStateObj->GetState());
 }
 
 void MediaDecoderStateMachine::VolumeChanged()
 {
   MOZ_ASSERT(OnTaskQueue());
   mMediaSink->SetVolume(mVolume);
 }
 
@@ -3658,17 +3656,17 @@ MediaDecoderStateMachine::DumpDebugInfo(
 
   // It is fine to capture a raw pointer here because MediaDecoder only call
   // this function before shutdown begins.
   nsCOMPtr<nsIRunnable> r = NS_NewRunnableFunction([this] () {
     mMediaSink->DumpDebugInfo();
     mStateObj->DumpDebugInfo();
     DUMP_LOG(
       "GetMediaTime=%lld GetClock=%lld mMediaSink=%p "
-      "mState=%s mPlayState=%d mSentFirstFrameLoadedEvent=%d IsPlaying=%d "
+      "state=%s mPlayState=%d mSentFirstFrameLoadedEvent=%d IsPlaying=%d "
       "mAudioStatus=%s mVideoStatus=%s mDecodedAudioEndTime=%lld mDecodedVideoEndTime=%lld "
       "mAudioCompleted=%d mVideoCompleted=%d",
       GetMediaTime(), mMediaSink->IsStarted() ? GetClock() : -1, mMediaSink.get(),
       ToStateStr(), mPlayState.Ref(), mSentFirstFrameLoadedEvent, IsPlaying(),
       AudioRequestStatus(), VideoRequestStatus(), mDecodedAudioEndTime, mDecodedVideoEndTime,
       mAudioCompleted, mVideoCompleted);
   });
 

--- a/dom/media/MediaDecoderStateMachine.h
+++ b/dom/media/MediaDecoderStateMachine.h
@@ -483,18 +483,16 @@ private:
 
   // Queue of audio frames. This queue is threadsafe, and is accessed from
   // the audio, decoder, state machine, and main threads.
   MediaQueue<MediaData> mAudioQueue;
   // Queue of video frames. This queue is threadsafe, and is accessed from
   // the decoder, state machine, and main threads.
   MediaQueue<MediaData> mVideoQueue;
 
-  State mState = DECODER_STATE_DECODING_METADATA;
-
   UniquePtr<StateObject> mStateObj;
 
   media::TimeUnit Duration() const { MOZ_ASSERT(OnTaskQueue()); return mDuration.Ref().ref(); }
 
   // Recomputes the canonical duration from various sources.
   void RecomputeDuration();