diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index e1d3714698..c90b2cdc44 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -262,7 +262,7 @@ enum CodecID {
     /* subtitle codecs */
     CODEC_ID_DVD_SUBTITLE= 0x17000,
     CODEC_ID_DVB_SUBTITLE,
-    CODEC_ID_TEXT,
+    CODEC_ID_TEXT,  /* raw UTF-8 text */
 
     CODEC_ID_MPEG2TS= 0x20000, /* _FAKE_ codec to indicate a raw MPEG-2 TS
                                 * stream (only used by libavformat) */