--- a/dom/media/MediaFormatReader.cpp
+++ b/dom/media/MediaFormatReader.cpp
@@ -2041,16 +2041,18 @@ MediaFormatReader::HandleDemuxedSamples(
         LOG("Decoder does not support recycling, recreate decoder.");
         // If flushing is required, it will clear our array of queued samples.
         // So make a copy now.
         nsTArray<RefPtr<MediaRawData>> samples{ Move(decoder.mQueuedSamples) };
         ShutdownDecoder(aTrack);
         if (sample->mKeyframe) {
           decoder.mQueuedSamples.AppendElements(Move(samples));
         }
+      } else if (decoder.HasWaitingPromise()) {
+        decoder.Flush();
       }
 
       decoder.mInfo = info;
 
       if (sample->mKeyframe) {
         ScheduleUpdate(aTrack);
       } else {
         auto time = TimeInterval(sample->mTime, sample->GetEndTime());