--- a/dom/media/flac/FlacDemuxer.cpp
+++ b/dom/media/flac/FlacDemuxer.cpp
@@ -671,17 +671,17 @@ FlacTrackDemuxer::Init()
   // Can seek there immediately to avoid reparsing it all.
   mSource.Seek(SEEK_SET, offset);
 
   // Find the first frame to fully initialise our parser.
   if (mParser->FindNextFrame(mSource)) {
     // Ensure that the next frame returned will be the first.
     mSource.Seek(SEEK_SET, mParser->FirstFrame().Offset());
     mParser->EndFrameSession();
-  } else if (!mParser->Info().IsValid()) {
+  } else if (!mParser->Info().IsValid() || !mParser->FirstFrame().IsValid()) {
     // We must find at least a frame to determine the metadata.
     // We can't play this stream.
     return false;
   }
 
   if (!mParser->Info().IsValid() || !mParser->Info().mDuration) {
     // Check if we can look at the last frame for the end time to determine the
     // duration when we don't have any.