diff --git a/content/media/AudioNodeStream.cpp b/content/media/AudioNodeStream.cpp
index 1c3f5018138f..8bc89902d4dc 100644
--- a/content/media/AudioNodeStream.cpp
+++ b/content/media/AudioNodeStream.cpp
@@ -189,7 +189,7 @@ AudioNodeStream::ObtainInputBlock(AudioChunk* aTmpChunk)
     if (a->IsFinishedOnGraphThread()) {
       continue;
     }
-    AudioChunk* chunk = a->mLastChunk;
+    AudioChunk* chunk = &a->mLastChunk;
     // XXX when we implement DelayNode, this will no longer be true and we'll
     // need to treat a null chunk (when the DelayNode hasn't had a chance
     // to produce data yet) as silence here.
@@ -268,11 +268,16 @@ AudioNodeStream::ProduceOutput(GraphTime aFrom, GraphTime aTo)
     }
   }
 
-  mLastChunk = segment->AppendAndConsumeChunk(&outputChunk);
+  mLastChunk = outputChunk;
+  if (mKind == MediaStreamGraph::EXTERNAL_STREAM) {
+    segment->AppendAndConsumeChunk(&outputChunk);
+  } else {
+    segment->AppendNullData(outputChunk.GetDuration());
+  }
 
   for (uint32_t j = 0; j < mListeners.Length(); ++j) {
     MediaStreamListener* l = mListeners[j];
-    AudioChunk copyChunk = *mLastChunk;
+    AudioChunk copyChunk = outputChunk;
     AudioSegment tmpSegment;
     tmpSegment.AppendAndConsumeChunk(&copyChunk);
     l->NotifyQueuedTrackChanges(Graph(), AUDIO_NODE_STREAM_TRACK_ID,
diff --git a/content/media/AudioNodeStream.h b/content/media/AudioNodeStream.h
index c9ad0c279bed..3595041dc64a 100644
--- a/content/media/AudioNodeStream.h
+++ b/content/media/AudioNodeStream.h
@@ -42,8 +42,11 @@ public:
   /**
    * Transfers ownership of aEngine to the new AudioNodeStream.
    */
-  explicit AudioNodeStream(AudioNodeEngine* aEngine)
-    : ProcessedMediaStream(nullptr), mEngine(aEngine), mLastChunk(nullptr)
+  AudioNodeStream(AudioNodeEngine* aEngine,
+                  MediaStreamGraph::AudioNodeStreamKind aKind)
+    : ProcessedMediaStream(nullptr),
+      mEngine(aEngine),
+      mKind(aKind)
   {
   }
   ~AudioNodeStream();
@@ -81,7 +84,9 @@ protected:
   // The engine that will generate output for this node.
   nsAutoPtr<AudioNodeEngine> mEngine;
   // The last block produced by this node.
-  AudioChunk* mLastChunk;
+  AudioChunk mLastChunk;
+  // Whether this is an internal or external stream
+  MediaStreamGraph::AudioNodeStreamKind mKind;
 };
 
 }
diff --git a/content/media/MediaStreamGraph.cpp b/content/media/MediaStreamGraph.cpp
index 96bcbb95df04..6703e20769f3 100644
--- a/content/media/MediaStreamGraph.cpp
+++ b/content/media/MediaStreamGraph.cpp
@@ -2002,9 +2002,10 @@ MediaStreamGraph::CreateTrackUnionStream(DOMMediaStream* aWrapper)
 }
 
 AudioNodeStream*
-MediaStreamGraph::CreateAudioNodeStream(AudioNodeEngine* aEngine)
+MediaStreamGraph::CreateAudioNodeStream(AudioNodeEngine* aEngine,
+                                        AudioNodeStreamKind aKind)
 {
-  AudioNodeStream* stream = new AudioNodeStream(aEngine);
+  AudioNodeStream* stream = new AudioNodeStream(aEngine, aKind);
   NS_ADDREF(stream);
   MediaStreamGraphImpl* graph = static_cast<MediaStreamGraphImpl*>(this);
   stream->SetGraphImpl(graph);
diff --git a/content/media/MediaStreamGraph.h b/content/media/MediaStreamGraph.h
index c0a35526c3cc..4e3ef0e2e73f 100644
--- a/content/media/MediaStreamGraph.h
+++ b/content/media/MediaStreamGraph.h
@@ -883,11 +883,16 @@ public:
    * particular tracks of each input stream.
    */
   ProcessedMediaStream* CreateTrackUnionStream(DOMMediaStream* aWrapper);
+  // Internal AudioNodeStreams can only pass their output to another
+  // AudioNode, whereas external AudioNodeStreams can pass their output
+  // to an nsAudioStream for playback.
+  enum AudioNodeStreamKind { INTERNAL_STREAM, EXTERNAL_STREAM };
   /**
    * Create a stream that will process audio for an AudioNode.
    * Takes ownership of aEngine.
    */
-  AudioNodeStream* CreateAudioNodeStream(AudioNodeEngine* aEngine);
+  AudioNodeStream* CreateAudioNodeStream(AudioNodeEngine* aEngine,
+                                         AudioNodeStreamKind aKind);
   /**
    * Returns the number of graph updates sent. This can be used to track
    * whether a given update has been processed by the graph thread and reflected
diff --git a/content/media/webaudio/AudioBufferSourceNode.cpp b/content/media/webaudio/AudioBufferSourceNode.cpp
index b63eccbf95ea..eb2d9f02b0b0 100644
--- a/content/media/webaudio/AudioBufferSourceNode.cpp
+++ b/content/media/webaudio/AudioBufferSourceNode.cpp
@@ -227,7 +227,8 @@ AudioBufferSourceNode::AudioBufferSourceNode(AudioContext* aContext)
   , mStartCalled(false)
 {
   SetProduceOwnOutput(true);
-  mStream = aContext->Graph()->CreateAudioNodeStream(new AudioBufferSourceNodeEngine());
+  mStream = aContext->Graph()->CreateAudioNodeStream(new AudioBufferSourceNodeEngine(),
+                                                     MediaStreamGraph::INTERNAL_STREAM);
   mStream->AddMainThreadListener(this);
 }
 
diff --git a/content/media/webaudio/AudioDestinationNode.cpp b/content/media/webaudio/AudioDestinationNode.cpp
index 07467d955ba8..e1ee3d258f33 100644
--- a/content/media/webaudio/AudioDestinationNode.cpp
+++ b/content/media/webaudio/AudioDestinationNode.cpp
@@ -31,7 +31,8 @@ NS_IMPL_CYCLE_COLLECTING_RELEASE(AudioDestinationNode)
 AudioDestinationNode::AudioDestinationNode(AudioContext* aContext, MediaStreamGraph* aGraph)
   : AudioNode(aContext)
 {
-  mStream = aGraph->CreateAudioNodeStream(new AudioNodeEngine());
+  mStream = aGraph->CreateAudioNodeStream(new AudioNodeEngine(),
+                                          MediaStreamGraph::EXTERNAL_STREAM);
   SetIsDOMBinding();
 }
 
diff --git a/content/media/webaudio/GainNode.cpp b/content/media/webaudio/GainNode.cpp
index 2cf83972d674..cc1d368b6fb8 100644
--- a/content/media/webaudio/GainNode.cpp
+++ b/content/media/webaudio/GainNode.cpp
@@ -118,7 +118,7 @@ GainNode::GainNode(AudioContext* aContext)
   , mGain(new AudioParam(this, SendGainToStream, 1.0f, 0.0f, 1.0f))
 {
   GainNodeEngine* engine = new GainNodeEngine(aContext->Destination());
-  mStream = aContext->Graph()->CreateAudioNodeStream(engine);
+  mStream = aContext->Graph()->CreateAudioNodeStream(engine, MediaStreamGraph::INTERNAL_STREAM);
   engine->SetSourceStream(static_cast<AudioNodeStream*> (mStream.get()));
 }
 
diff --git a/content/media/webaudio/PannerNode.cpp b/content/media/webaudio/PannerNode.cpp
index cac8ce819b89..fa6efb28e7a1 100644
--- a/content/media/webaudio/PannerNode.cpp
+++ b/content/media/webaudio/PannerNode.cpp
@@ -121,7 +121,8 @@ PannerNode::PannerNode(AudioContext* aContext)
   , mConeOuterAngle(360.)
   , mConeOuterGain(0.)
 {
-  mStream = aContext->Graph()->CreateAudioNodeStream(new PannerNodeEngine());
+  mStream = aContext->Graph()->CreateAudioNodeStream(new PannerNodeEngine(),
+                                                     MediaStreamGraph::INTERNAL_STREAM);
   // We should register once we have set up our stream and engine.
   Context()->Listener()->RegisterPannerNode(this);
 }