--- a/dom/media/mediasource/MediaSourceReader.cpp
+++ b/dom/media/mediasource/MediaSourceReader.cpp
@@ -839,17 +839,22 @@ MediaSourceReader::OnAudioSeekFailed(nsr
 
 void
 MediaSourceReader::AttemptSeek()
 {
   // Make sure we don't hold the monitor while calling into the reader
   // Seek methods since it can deadlock.
   {
     ReentrantMonitorAutoEnter mon(mDecoder->GetReentrantMonitor());
-    if (!mWaitingForSeekData || !TrackBuffersContainTime(mPendingSeekTime)) {
+    if (!mWaitingForSeekData) {
+      return;
+    }
+    if (!TrackBuffersContainTime(mPendingSeekTime)) {
+      mVideoSourceDecoder = nullptr;
+      mAudioSourceDecoder = nullptr;
       return;
     }
     mWaitingForSeekData = false;
   }
 
   ResetDecode();
   for (uint32_t i = 0; i < mTrackBuffers.Length(); ++i) {
     mTrackBuffers[i]->ResetDecode();