diff --git a/libavformat/isom.c b/libavformat/isom.c
index 0e040c4546..23d716fef3 100644
--- a/libavformat/isom.c
+++ b/libavformat/isom.c
@@ -195,6 +195,7 @@ const AVCodecTag codec_movaudio_tags[] = {
     { CODEC_ID_MACE3, MKTAG('M', 'A', 'C', '3') }, /* Macintosh Audio Compression and Expansion 3:1 */
     { CODEC_ID_MACE6, MKTAG('M', 'A', 'C', '6') }, /* Macintosh Audio Compression and Expansion 6:1 */
 
+    { CODEC_ID_MP1, MKTAG('.', 'm', 'p', '1') }, /* MPEG layer 1 */
     { CODEC_ID_MP2, MKTAG('.', 'm', 'p', '2') }, /* MPEG layer 2 */
 
     { CODEC_ID_MP3, MKTAG('.', 'm', 'p', '3') }, /* MPEG layer 3 */ /* sample files at http://www.3ivx.com/showcase.html use this tag */