--- a/toolkit/components/mediasniffer/nsMediaSniffer.cpp
+++ b/toolkit/components/mediasniffer/nsMediaSniffer.cpp
@@ -40,16 +40,17 @@ nsMediaSnifferEntry nsMediaSniffer::sSni
   PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "fLaC", AUDIO_FLAC)
 };
 
 // For a complete list of file types, see http://www.ftyps.com/index.html
 nsMediaSnifferEntry sFtypEntries[] = {
   PATTERN_ENTRY("\xFF\xFF\xFF", "mp4", VIDEO_MP4), // Could be mp41 or mp42.
   PATTERN_ENTRY("\xFF\xFF\xFF", "avc", VIDEO_MP4), // Could be avc1, avc2, ...
   PATTERN_ENTRY("\xFF\xFF\xFF", "3gp", VIDEO_3GPP), // Could be 3gp4, 3gp5, ...
+  PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "M4V ", VIDEO_MP4),
   PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "M4A ", AUDIO_MP4),
   PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "M4P ", AUDIO_MP4),
   PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "qt  ", VIDEO_QUICKTIME),
   PATTERN_ENTRY("\xFF\xFF\xFF", "iso", VIDEO_MP4), // Could be isom or iso2.
   PATTERN_ENTRY("\xFF\xFF\xFF\xFF", "mmp4", VIDEO_MP4),
 };
 
 static bool MatchesBrands(const uint8_t aData[4], nsACString& aSniffedType)