--- a/dom/media/MediaDecoderStateMachine.cpp
+++ b/dom/media/MediaDecoderStateMachine.cpp
@@ -754,17 +754,16 @@ MediaDecoderStateMachine::MaybeFinishDec
     return false;
   }
   FinishDecodeFirstFrame();
   if (!mQueuedSeek.Exists()) {
     return false;
   }
 
   // We can now complete the pending seek.
-  SetState(DECODER_STATE_SEEKING);
   InitiateSeek(Move(mQueuedSeek));
   return true;
 }
 
 void
 MediaDecoderStateMachine::OnVideoDecoded(MediaData* aVideoSample,
                                          TimeStamp aDecodeStartTime)
 {
@@ -1262,17 +1261,16 @@ void MediaDecoderStateMachine::StartDeco
       // the first samples in order to determine the media start time,
       // we have the start time from last time we loaded.
       // FinishDecodeFirstFrame will be launched upon completion of the seek when
       // we have data ready to play.
       MOZ_ASSERT(mQueuedSeek.Exists() && mSentFirstFrameLoadedEvent,
                  "Return from dormant must have queued seek");
     }
     if (mQueuedSeek.Exists()) {
-      SetState(DECODER_STATE_SEEKING);
       InitiateSeek(Move(mQueuedSeek));
       return;
     }
   }
 
   mDecodeStartTime = TimeStamp::Now();
 
   CheckIfDecodeComplete();
@@ -1515,22 +1513,20 @@ MediaDecoderStateMachine::Seek(SeekTarge
     DECODER_LOG("Seek() Not Enough Data to continue at this stage, queuing seek");
     mQueuedSeek.RejectIfExists(__func__);
     mQueuedSeek.mTarget = aTarget;
     return mQueuedSeek.mPromise.Ensure(__func__);
   }
   mQueuedSeek.RejectIfExists(__func__);
 
   DECODER_LOG("Changed state to SEEKING (to %lld)", aTarget.GetTime().ToMicroseconds());
-  SetState(DECODER_STATE_SEEKING);
 
   SeekJob seekJob;
   seekJob.mTarget = aTarget;
-  InitiateSeek(Move(seekJob));
-  return mCurrentSeek.mPromise.Ensure(__func__);
+  return InitiateSeek(Move(seekJob));
 }
 
 RefPtr<MediaDecoder::SeekPromise>
 MediaDecoderStateMachine::InvokeSeek(SeekTarget aTarget)
 {
   return InvokeAsync(OwnerThread(), this, __func__,
                      &MediaDecoderStateMachine::Seek, aTarget);
 }
@@ -1600,65 +1596,69 @@ MediaDecoderStateMachine::DispatchDecode
   if (needIdle) {
     DECODER_LOG("Dispatching SetIdle() audioQueue=%lld videoQueue=%lld",
                 GetDecodedAudioDuration(),
                 VideoQueue().Duration());
     mReader->SetIdle();
   }
 }
 
-void
+RefPtr<MediaDecoder::SeekPromise>
 MediaDecoderStateMachine::InitiateSeek(SeekJob aSeekJob)
 {
   MOZ_ASSERT(OnTaskQueue());
 
+  SetState(DECODER_STATE_SEEKING);
+
   // Discard the existing seek task.
   DiscardSeekTaskIfExist();
 
   mSeekTaskRequest.DisconnectIfExists();
 
   // SeekTask will register its callbacks to MediaDecoderReaderWrapper.
   CancelMediaDecoderReaderWrapperCallback();
 
   // Create a new SeekTask instance for the incoming seek task.
-  MOZ_ASSERT(!mCurrentSeek.Exists());
-  mCurrentSeek = Move(aSeekJob);
-  if (mCurrentSeek.mTarget.IsAccurate() || mCurrentSeek.mTarget.IsFast()) {
+  if (aSeekJob.mTarget.IsAccurate() || aSeekJob.mTarget.IsFast()) {
     mSeekTask = new AccurateSeekTask(mDecoderID, OwnerThread(),
-                                     mReader.get(), mCurrentSeek.mTarget,
+                                     mReader.get(), aSeekJob.mTarget,
                                      mInfo, Duration(), GetMediaTime());
-  } else if (mCurrentSeek.mTarget.IsNextFrame()) {
+  } else if (aSeekJob.mTarget.IsNextFrame()) {
     mSeekTask = new NextFrameSeekTask(mDecoderID, OwnerThread(), mReader.get(),
-                                      mCurrentSeek.mTarget, mInfo, Duration(),
+                                      aSeekJob.mTarget, mInfo, Duration(),
                                       GetMediaTime(), AudioQueue(), VideoQueue());
   } else {
     MOZ_DIAGNOSTIC_ASSERT(false, "Cannot handle this seek task.");
   }
 
   // Stop playback now to ensure that while we're outside the monitor
   // dispatching SeekingStarted, playback doesn't advance and mess with
   // mCurrentPosition that we've setting to seekTime here.
   StopPlayback();
 
-  // mCurrentSeek.mTarget.mTime might be different from
+  // aSeekJob.mTarget.mTime might be different from
   // mSeekTask->GetSeekTarget().mTime because the seek task might clamp the seek
   // target to [0, duration]. We want to update the playback position to the
   // clamped value.
   UpdatePlaybackPositionInternal(mSeekTask->GetSeekTarget().GetTime().ToMicroseconds());
 
-  mOnSeekingStart.Notify(mCurrentSeek.mTarget.mEventVisibility);
+  mOnSeekingStart.Notify(aSeekJob.mTarget.mEventVisibility);
 
   // Reset our state machine and decoding pipeline before seeking.
   if (mSeekTask->NeedToResetMDSM()) { Reset(); }
 
   // Do the seek.
   mSeekTaskRequest.Begin(mSeekTask->Seek(Duration())
     ->Then(OwnerThread(), __func__, this,
            &MediaDecoderStateMachine::OnSeekTaskResolved,
            &MediaDecoderStateMachine::OnSeekTaskRejected));
+
+  MOZ_ASSERT(!mCurrentSeek.Exists());
+  mCurrentSeek = Move(aSeekJob);
+  return mCurrentSeek.mPromise.Ensure(__func__);
 }
 
 void
 MediaDecoderStateMachine::OnSeekTaskResolved(SeekTaskResolveValue aValue)
 {
   MOZ_ASSERT(OnTaskQueue());
   MOZ_ASSERT(mState == DECODER_STATE_SEEKING);
 

--- a/dom/media/MediaDecoderStateMachine.h
+++ b/dom/media/MediaDecoderStateMachine.h
@@ -504,18 +504,17 @@ protected:
   // Dispatches a LoadedMetadataEvent.
   // This is threadsafe and can be called on any thread.
   // The decoder monitor must be held.
   void EnqueueLoadedMetadataEvent();
 
   void EnqueueFirstFrameLoadedEvent();
 
   // Clears any previous seeking state and initiates a new seek on the decoder.
-  // The decoder monitor must be held.
-  void InitiateSeek(SeekJob aSeekJob);
+  RefPtr<MediaDecoder::SeekPromise> InitiateSeek(SeekJob aSeekJob);
 
   // Clears any previous seeking state and initiates a seek on the decoder to
   // resync the video and audio positions, when recovering from video decoding
   // being suspended in background or from audio and video decoding being
   // suspended due to the decoder limit.
   void InitiateDecodeRecoverySeek(TrackSet aTracks);
 
   nsresult DispatchAudioDecodeTaskIfNeeded();