diff --git a/libavcodec/zmbv.c b/libavcodec/zmbv.c
index a36a844b1f..9df0d53525 100644
--- a/libavcodec/zmbv.c
+++ b/libavcodec/zmbv.c
@@ -497,8 +497,11 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPac
      }
 
      if (c->comp == 0) { //Uncompressed data
+         if (c->decomp_size < len) {
+             av_log(avctx, AV_LOG_ERROR, "Buffer too small\n");
+             return AVERROR_INVALIDDATA;
+         }
          memcpy(c->decomp_buf, buf, len);
-         c->decomp_size = 1;
      } else { // ZLIB-compressed data
         c->zstream.total_in = c->zstream.total_out = 0;
         c->zstream.next_in = buf;