diff --git a/dom/media/mediasource/MediaSourceDecoder.cpp b/dom/media/mediasource/MediaSourceDecoder.cpp
index c35b1f35e74..09f8520a731 100644
--- a/dom/media/mediasource/MediaSourceDecoder.cpp
+++ b/dom/media/mediasource/MediaSourceDecoder.cpp
@@ -240,6 +240,9 @@ MediaSourceDecoder::DoSetMediaSourceDuration(double aDuration)
     mDecoderStateMachine->SetDuration(INT64_MAX);
     mMediaSourceDuration = PositiveInfinity<double>();
   }
+  if (mReader) {
+    mReader->SetMediaSourceDuration(mMediaSourceDuration);
+  }
 }
 
 void
diff --git a/dom/media/mediasource/MediaSourceReader.cpp b/dom/media/mediasource/MediaSourceReader.cpp
index 5b56f84f610..7effd07174b 100644
--- a/dom/media/mediasource/MediaSourceReader.cpp
+++ b/dom/media/mediasource/MediaSourceReader.cpp
@@ -56,6 +56,7 @@ MediaSourceReader::MediaSourceReader(MediaSourceDecoder* aDecoder)
   , mDropAudioBeforeThreshold(false)
   , mDropVideoBeforeThreshold(false)
   , mEnded(false)
+  , mMediaSourceDuration(0)
   , mHasEssentialTrackBuffers(false)
 #ifdef MOZ_FMP4
   , mSharedDecoderManager(new SharedDecoderManager())
@@ -133,7 +134,7 @@ MediaSourceReader::RequestAudioData()
       break;
     case READER_ERROR:
       if (mLastAudioTime) {
-        CheckForWaitOrEndOfStream(MediaData::AUDIO_DATA);
+        CheckForWaitOrEndOfStream(MediaData::AUDIO_DATA, mLastAudioTime);
         break;
       }
       // Fallback to using current reader
@@ -238,7 +239,7 @@ MediaSourceReader::OnAudioNotDecoded(NotDecodedReason aReason)
     return;
   }
 
-  CheckForWaitOrEndOfStream(MediaData::AUDIO_DATA);
+  CheckForWaitOrEndOfStream(MediaData::AUDIO_DATA, mLastAudioTime);
 }
 
 
@@ -273,7 +274,7 @@ MediaSourceReader::RequestVideoData(bool aSkipToNextKeyframe, int64_t aTimeThres
       break;
     case READER_ERROR:
       if (mLastVideoTime) {
-        CheckForWaitOrEndOfStream(MediaData::VIDEO_DATA);
+        CheckForWaitOrEndOfStream(MediaData::VIDEO_DATA, mLastVideoTime);
         break;
       }
       // Fallback to using current reader.
@@ -355,14 +356,14 @@ MediaSourceReader::OnVideoNotDecoded(NotDecodedReason aReason)
     return;
   }
 
-  CheckForWaitOrEndOfStream(MediaData::VIDEO_DATA);
+  CheckForWaitOrEndOfStream(MediaData::VIDEO_DATA, mLastVideoTime);
 }
 
 void
-MediaSourceReader::CheckForWaitOrEndOfStream(MediaData::Type aType)
+MediaSourceReader::CheckForWaitOrEndOfStream(MediaData::Type aType, int64_t aTime)
 {
   // If the entire MediaSource is done, generate an EndOfStream.
-  if (IsEnded()) {
+  if (IsNearEnd(aTime)) {
     if (aType == MediaData::AUDIO_DATA) {
       mAudioPromise.Reject(END_OF_STREAM, __func__);
     } else {
@@ -946,6 +947,20 @@ MediaSourceReader::IsEnded()
   return mEnded;
 }
 
+bool
+MediaSourceReader::IsNearEnd(int64_t aTime)
+{
+  ReentrantMonitorAutoEnter mon(mDecoder->GetReentrantMonitor());
+  return mEnded && aTime >= (mMediaSourceDuration * USECS_PER_S - EOS_FUZZ_US);
+}
+
+void
+MediaSourceReader::SetMediaSourceDuration(double aDuration)
+{
+  ReentrantMonitorAutoEnter mon(mDecoder->GetReentrantMonitor());
+  mMediaSourceDuration = aDuration;
+}
+
 #ifdef MOZ_EME
 nsresult
 MediaSourceReader::SetCDMProxy(CDMProxy* aProxy)
diff --git a/dom/media/mediasource/MediaSourceReader.h b/dom/media/mediasource/MediaSourceReader.h
index 5d6322d6438..8d547af9194 100644
--- a/dom/media/mediasource/MediaSourceReader.h
+++ b/dom/media/mediasource/MediaSourceReader.h
@@ -129,6 +129,10 @@ public:
 
   // Return true if the Ended method has been called
   bool IsEnded();
+  bool IsNearEnd(int64_t aTime /* microseconds */);
+
+  // Set the duration of the attached mediasource element.
+  void SetMediaSourceDuration(double aDuration /* seconds */);
 
 #ifdef MOZ_EME
   nsresult SetCDMProxy(CDMProxy* aProxy);
@@ -159,7 +163,7 @@ private:
   void RequestVideoDataFailed(nsresult aResult);
   // Will reject the MediaPromise with END_OF_STREAM if mediasource has ended
   // or with WAIT_FOR_DATA otherwise.
-  void CheckForWaitOrEndOfStream(MediaData::Type aType);
+  void CheckForWaitOrEndOfStream(MediaData::Type aType, int64_t aTime /* microseconds */);
 
   // Return a reader from the set available in aTrackDecoders that has data
   // available in the range requested by aTarget.
@@ -210,6 +214,7 @@ private:
   bool mDropVideoBeforeThreshold;
 
   bool mEnded;
+  double mMediaSourceDuration;
 
   bool mHasEssentialTrackBuffers;