--- a/dom/media/mediasink/AudioSink.cpp
+++ b/dom/media/mediasink/AudioSink.cpp
@@ -226,17 +226,19 @@ AudioSink::GetEndTime() const
     MonitorAutoLock mon(mMonitor);
     written = mWritten;
   }
   TimeUnit played = FramesToTimeUnit(written, mOutputRate) + mStartTime;
   if (!played.IsValid()) {
     NS_WARNING("Int overflow calculating audio end time");
     return TimeUnit::Zero();
   }
-  return played;
+  // As we may be resampling, rounding errors may occur. Ensure we never get
+  // past the original end time.
+  return std::min(mLastEndTime, played);
 }
 
 UniquePtr<AudioStream::Chunk>
 AudioSink::PopFrames(uint32_t aFrames)
 {
   class Chunk : public AudioStream::Chunk {
   public:
     Chunk(AudioData* aBuffer, uint32_t aFrames, AudioDataValue* aData)