diff --git a/libavcodec/h263dec.c b/libavcodec/h263dec.c
index eae29fa438..c082af1c52 100644
--- a/libavcodec/h263dec.c
+++ b/libavcodec/h263dec.c
@@ -318,6 +318,7 @@ static int decode_slice(MpegEncContext *s)
 
     av_assert1(s->mb_x == 0 && s->mb_y == s->mb_height);
 
+    // Detect incorrect padding with wrong stuffing codes used by NEC N-02B
     if (s->codec_id == AV_CODEC_ID_MPEG4         &&
         (s->workaround_bugs & FF_BUG_AUTODETECT) &&
         get_bits_left(&s->gb) >= 48              &&