diff --git a/libavcodec/mpeg12dec.c b/libavcodec/mpeg12dec.c
index 62aaec1424..07efd6afa9 100644
--- a/libavcodec/mpeg12dec.c
+++ b/libavcodec/mpeg12dec.c
@@ -1046,7 +1046,7 @@ static int mpeg_decode_mb(MpegEncContext *s, int16_t block[12][64])
 
             cbp = get_vlc2(&s->gb, ff_mb_pat_vlc.table, MB_PAT_VLC_BITS, 1);
             if (mb_block_count > 6) {
-                cbp <<= mb_block_count - 6;
+                cbp *= 1 << mb_block_count - 6;
                 cbp  |= get_bits(&s->gb, mb_block_count - 6);
                 s->bdsp.clear_blocks(s->block[6]);
             }