--- a/dom/media/mediasource/MediaSourceDemuxer.cpp
+++ b/dom/media/mediasource/MediaSourceDemuxer.cpp
@@ -4,16 +4,17 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "MediaSourceDemuxer.h"
 
 #include "MediaSourceUtils.h"
 #include "OpusDecoder.h"
 #include "SourceBufferList.h"
+#include "VorbisDecoder.h"
 #include "nsPrintfCString.h"
 
 #include <algorithm>
 #include <limits>
 #include <stdint.h>
 
 namespace mozilla {
 
@@ -302,17 +303,18 @@ MediaSourceTrackDemuxer::MediaSourceTrac
                                                  TrackInfo::TrackType aType,
                                                  TrackBuffersManager* aManager)
   : mParent(aParent)
   , mManager(aManager)
   , mType(aType)
   , mMonitor("MediaSourceTrackDemuxer")
   , mReset(true)
   , mPreRoll(TimeUnit::FromMicroseconds(
-      OpusDataDecoder::IsOpus(mParent->GetTrackInfo(mType)->mMimeType)
+      OpusDataDecoder::IsOpus(mParent->GetTrackInfo(mType)->mMimeType) ||
+      VorbisDataDecoder::IsVorbis(mParent->GetTrackInfo(mType)->mMimeType)
       ? 80000
       : mParent->GetTrackInfo(mType)->mMimeType.EqualsLiteral("audio/mp4a-latm")
         // AAC encoder delay is by default 2112 audio frames.
         // See https://developer.apple.com/library/content/documentation/QuickTime/QTFF/QTFFAppenG/QTFFAppenG.html
         // So we always seek 2112 frames
         ? (2112 * 1000000ULL
            / mParent->GetTrackInfo(mType)->GetAsAudioInfo()->mRate)
         : 0))