diff --git a/libavformat/mpjpegdec.c b/libavformat/mpjpegdec.c
index 3446f2a4f1..7a6bbe491b 100644
--- a/libavformat/mpjpegdec.c
+++ b/libavformat/mpjpegdec.c
@@ -351,8 +351,8 @@ static int mpjpeg_read_packet(AVFormatContext *s, AVPacket *pkt)
             do {
                 if (!memcmp(start, mpjpeg->searchstr, mpjpeg->searchstr_len)) {
                     // got the boundary! rewind the stream
-                    avio_seek(s->pb, -(len-2), SEEK_CUR);
-                    pkt->size -= (len-2);
+                    avio_seek(s->pb, -len, SEEK_CUR);
+                    pkt->size -= len;
                     return pkt->size;
                 }
                 len--;