--- a/dom/media/webaudio/AudioNodeExternalInputStream.cpp
+++ b/dom/media/webaudio/AudioNodeExternalInputStream.cpp
@@ -147,23 +147,28 @@ AudioNodeExternalInputStream::ProcessInp
     return;
   }
 
   MOZ_ASSERT(mInputs.Length() == 1);
 
   MediaStream* source = mInputs[0]->GetSource();
   AutoTArray<AudioSegment,1> audioSegments;
   uint32_t inputChannels = 0;
-  for (StreamTracks::TrackIter tracks(source->mTracks, MediaSegment::AUDIO);
+  for (StreamTracks::TrackIter tracks(source->mTracks);
        !tracks.IsEnded(); tracks.Next()) {
     const StreamTracks::Track& inputTrack = *tracks;
     if (!mInputs[0]->PassTrackThrough(tracks->GetID())) {
       continue;
     }
 
+    if (inputTrack.GetSegment()->GetType() == MediaSegment::VIDEO) {
+      MOZ_ASSERT(false, "AudioNodeExternalInputStream shouldn't have video tracks");
+      continue;
+    }
+
     const AudioSegment& inputSegment =
         *static_cast<AudioSegment*>(inputTrack.GetSegment());
     if (inputSegment.IsNull()) {
       continue;
     }
 
     AudioSegment& segment = *audioSegments.AppendElement();
     GraphTime next;