diff --git a/libavformat/asf-enc.c b/libavformat/asf-enc.c
index 5121965b25..a12cda1e7c 100644
--- a/libavformat/asf-enc.c
+++ b/libavformat/asf-enc.c
@@ -199,7 +199,7 @@ static const AVCodecTag codec_asf_bmp_tags[] = {
 static void put_guid(ByteIOContext *s, const GUID *g)
 {
     assert(sizeof(*g) == 16);
-    put_buffer(s, g, sizeof(*g));
+    put_buffer(s, *g, sizeof(*g));
 }
 
 static void put_str16_nolen(ByteIOContext *s, const char *tag);