diff --git a/libavcodec/anm.c b/libavcodec/anm.c
index ab6a3994e9..778f38413e 100644
--- a/libavcodec/anm.c
+++ b/libavcodec/anm.c
@@ -119,6 +119,9 @@ static int decode_frame(AVCodecContext *avctx,
     uint8_t *dst, *dst_end;
     int count, ret;
 
+    if (buf_size < 7)
+        return AVERROR_INVALIDDATA;
+
     if ((ret = ff_reget_buffer(avctx, s->frame)) < 0)
         return ret;
     dst     = s->frame->data[0];