--- a/dom/media/platforms/agnostic/VorbisDecoder.cpp
+++ b/dom/media/platforms/agnostic/VorbisDecoder.cpp
@@ -126,38 +126,42 @@ VorbisDataDecoder::DecodeHeader(const un
                                     &mVorbisComment,
                                     &pkt);
   return r == 0 ? NS_OK : NS_ERROR_FAILURE;
 }
 
 nsresult
 VorbisDataDecoder::Input(MediaRawData* aSample)
 {
+  MOZ_ASSERT(mCallback->OnReaderTaskQueue());
   mTaskQueue->Dispatch(NewRunnableMethod<RefPtr<MediaRawData>>(
                        this, &VorbisDataDecoder::ProcessDecode, aSample));
 
   return NS_OK;
 }
 
 void
 VorbisDataDecoder::ProcessDecode(MediaRawData* aSample)
 {
+  MOZ_ASSERT(mTaskQueue->IsCurrentThreadIn());
   if (mIsFlushing) {
     return;
   }
   if (DoDecode(aSample) == -1) {
     mCallback->Error();
   } else if (mTaskQueue->IsEmpty()) {
     mCallback->InputExhausted();
   }
 }
 
 int
 VorbisDataDecoder::DoDecode(MediaRawData* aSample)
 {
+  MOZ_ASSERT(mTaskQueue->IsCurrentThreadIn());
+
   const unsigned char* aData = aSample->Data();
   size_t aLength = aSample->Size();
   int64_t aOffset = aSample->mOffset;
   uint64_t aTstampUsecs = aSample->mTime;
   int64_t aTotalFrames = 0;
 
   MOZ_ASSERT(mPacketCount >= 3);
 
@@ -256,29 +260,32 @@ VorbisDataDecoder::DoDecode(MediaRawData
   }
 
   return aTotalFrames > 0 ? 1 : 0;
 }
 
 void
 VorbisDataDecoder::ProcessDrain()
 {
+  MOZ_ASSERT(mTaskQueue->IsCurrentThreadIn());
   mCallback->DrainComplete();
 }
 
 nsresult
 VorbisDataDecoder::Drain()
 {
+  MOZ_ASSERT(mCallback->OnReaderTaskQueue());
   mTaskQueue->Dispatch(NewRunnableMethod(this, &VorbisDataDecoder::ProcessDrain));
   return NS_OK;
 }
 
 nsresult
 VorbisDataDecoder::Flush()
 {
+  MOZ_ASSERT(mCallback->OnReaderTaskQueue());
   mIsFlushing = true;
   nsCOMPtr<nsIRunnable> r = NS_NewRunnableFunction([this] () {
     // Ignore failed results from vorbis_synthesis_restart. They
     // aren't fatal and it fails when ResetDecode is called at a
     // time when no vorbis data has been read.
     vorbis_synthesis_restart(&mVorbisDsp);
     mLastFrameTime.reset();
   });