diff --git a/libavformat/mp3.c b/libavformat/mp3.c
index 540adfc197..d6d5b2c4e3 100644
--- a/libavformat/mp3.c
+++ b/libavformat/mp3.c
@@ -585,7 +585,7 @@ static int mp3_write_header(struct AVFormatContext *s)
     char yeartxt[10];
 
     if(s->track)
-        snprintf(tracktxt, sizeof(tracktxt) - 1, "%d", s->track);
+        snprintf(tracktxt, sizeof(tracktxt)    , "%d", s->track);
     if(s->year)
         snprintf( yeartxt, sizeof(yeartxt)     , "%d", s->year );