diff --git a/libavcodec/cdgraphics.c b/libavcodec/cdgraphics.c
index 71d9da7ee2..218d68a11c 100644
--- a/libavcodec/cdgraphics.c
+++ b/libavcodec/cdgraphics.c
@@ -296,7 +296,9 @@ static int cdg_decode_frame(AVCodecContext *avctx,
     inst    = bytestream_get_byte(&buf);
     inst    &= CDG_MASK;
     buf += 2;  /// skipping 2 unneeded bytes
-    bytestream_get_buffer(&buf, cdg_data, buf_size - CDG_HEADER_SIZE);
+
+    if (buf_size > CDG_HEADER_SIZE)
+        bytestream_get_buffer(&buf, cdg_data, buf_size - CDG_HEADER_SIZE);
 
     if ((command & CDG_MASK) == CDG_COMMAND) {
         switch (inst) {