--- a/dom/media/MediaDecoderStateMachine.cpp
+++ b/dom/media/MediaDecoderStateMachine.cpp
@@ -1834,17 +1834,17 @@ void
 MediaDecoderStateMachine::
 DecodeMetadataState::OnMetadataRead(MetadataHolder* aMetadata)
 {
   mMetadataRequest.Complete();
 
   // Set mode to PLAYBACK after reading metadata.
   Resource()->SetReadMode(MediaCacheStream::MODE_PLAYBACK);
 
-  mMaster->mInfo = Some(aMetadata->mInfo);
+  mMaster->mInfo.emplace(aMetadata->mInfo);
   mMaster->mMetadataTags = aMetadata->mTags.forget();
   mMaster->mMediaSeekable = Info().mMediaSeekable;
   mMaster->mMediaSeekableOnlyInBufferedRanges = Info().mMediaSeekableOnlyInBufferedRanges;
 
   if (Info().mMetadataDuration.isSome()) {
     mMaster->RecomputeDuration();
   } else if (Info().mUnadjustedMetadataEndTime.isSome()) {
     const TimeUnit unadjusted = Info().mUnadjustedMetadataEndTime.ref();