--- a/content/media/MediaStreamGraph.cpp
+++ b/content/media/MediaStreamGraph.cpp
@@ -694,17 +694,18 @@ MediaStreamGraphImpl::RecomputeBlockingA
     MediaStream* stream = aStreams[i];
     stream->mBlockInThisPhase = false;
   }
 
   for (uint32_t i = 0; i < aStreams.Length(); ++i) {
     MediaStream* stream = aStreams[i];
 
     if (stream->mFinished) {
-      GraphTime endTime = StreamTimeToGraphTime(stream, stream->GetBufferEnd());
+      GraphTime endTime = StreamTimeToGraphTime(stream,
+         stream->GetStreamBuffer().GetAllTracksEnd());
       if (endTime <= aTime) {
         STREAM_LOG(PR_LOG_DEBUG+1, ("MediaStream %p is blocked due to being finished", stream));
         // We'll block indefinitely
         MarkStreamBlocking(stream);
         *aEnd = aEndBlockingDecisions;
         continue;
       } else {
         STREAM_LOG(PR_LOG_DEBUG+1, ("MediaStream %p is finished, but not blocked yet (end at %f, with blocking at %f)",