diff --git a/libavformat/aiff.c b/libavformat/aiff.c
index c8e89c7c1d16e025dc727835425b68d221a793db..19443bb206e8f0d70d71c71690f6e8592d98252c 100644
--- a/libavformat/aiff.c
+++ b/libavformat/aiff.c
@@ -354,8 +354,8 @@ static int aiff_read_header(AVFormatContext *s,
 
             case MKTAG('S', 'S', 'N', 'D'):     /* Sampled sound chunk */
                 offset = get_be32(pb);      /* Offset of sound data */
-                offset += url_ftell(pb);    /* Compute absolute data offset */
                 get_be32(pb);               /* BlockSize... don't care */
+                offset += url_ftell(pb);    /* Compute absolute data offset */
                 if (st->codec->codec_id)    /* Assume COMM already parsed */
                     goto got_sound;
                 if (url_is_streamed(pb)) {