--- a/dom/media/MediaDecoderStateMachine.cpp
+++ b/dom/media/MediaDecoderStateMachine.cpp
@@ -2347,23 +2347,16 @@ nsresult MediaDecoderStateMachine::RunSt
                      "Must have timer scheduled");
         return NS_OK;
       }
 
       // StopPlayback in order to reset the IsPlaying() state so audio
       // is restarted correctly.
       StopPlayback();
 
-      if (mState != DECODER_STATE_COMPLETED) {
-        // While we're presenting a frame we can change state. Whatever changed
-        // our state should have scheduled another state machine run.
-        NS_ASSERTION(IsStateMachineScheduled(), "Must have timer scheduled");
-        return NS_OK;
-      }
-
       if (mPlayState == MediaDecoder::PLAY_STATE_PLAYING &&
           !mSentPlaybackEndedEvent)
       {
         int64_t clockTime = std::max(AudioEndTime(), VideoEndTime());
         clockTime = std::max(int64_t(0), std::max(clockTime, Duration().ToMicroseconds()));
         UpdatePlaybackPosition(clockTime);
 
         // Ensure readyState is updated before firing the 'ended' event.