diff --git a/libavformat/mp3.c b/libavformat/mp3.c
index 2d24d52992..b8b83b4b25 100644
--- a/libavformat/mp3.c
+++ b/libavformat/mp3.c
@@ -193,12 +193,12 @@ static int id3v1_create_tag(AVFormatContext *s, uint8_t *buf)
     count += id3v1_set_string(s, "album",   buf + 63, 30);
     count += id3v1_set_string(s, "year",    buf + 93,  4);
     count += id3v1_set_string(s, "comment", buf + 97, 30);
-    buf[127] = 0xFF; /* default to unknown genre */
     if ((tag = av_metadata_get(s->metadata, "track", NULL, 0))) {
         buf[125] = 0;
         buf[126] = atoi(tag->value);
         count++;
     }
+    buf[127] = 0xFF; /* default to unknown genre */
     if ((tag = av_metadata_get(s->metadata, "genre", NULL, 0))) {
         for(i = 0; i <= ID3v1_GENRE_MAX; i++) {
             if (!strcasecmp(tag->value, ff_id3v1_genre_str[i])) {