diff --git a/libavcodec/smacker.c b/libavcodec/smacker.c
index 813eb862c0..6b1faec09e 100644
--- a/libavcodec/smacker.c
+++ b/libavcodec/smacker.c
@@ -448,6 +448,8 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
         case SMK_BLK_FULL:
             mode = 0;
             if(avctx->codec_tag == MKTAG('S', 'M', 'K', '4')) { // In case of Smacker v4 we have three modes
+                if (get_bits_left(&gb) < 1)
+                    return AVERROR_INVALIDDATA;
                 if(get_bits1(&gb)) mode = 1;
                 else if(get_bits1(&gb)) mode = 2;
             }