diff --git a/libavformat/asf.c b/libavformat/asf.c
index dd64a3fbd0..80d24dbf43 100644
--- a/libavformat/asf.c
+++ b/libavformat/asf.c
@@ -117,6 +117,10 @@ const ff_asf_guid ff_asf_marker_header = {
     0x01, 0xCD, 0x87, 0xF4, 0x51, 0xA9, 0xCF, 0x11, 0x8E, 0xE6, 0x00, 0xC0, 0x0C, 0x20, 0x53, 0x65
 };
 
+const ff_asf_guid ff_asf_reserved_4 = {
+        0x20, 0xdb, 0xfe, 0x4c, 0xf6, 0x75, 0xCF, 0x11, 0x9c, 0x0f, 0x00, 0xa0, 0xc9, 0x03, 0x49, 0xcb
+};
+
 /* I am not a number !!! This GUID is the one found on the PC used to
  * generate the stream */
 const ff_asf_guid ff_asf_my_guid = {
diff --git a/libavformat/asf.h b/libavformat/asf.h
index 30d6c1e488..414baef11e 100644
--- a/libavformat/asf.h
+++ b/libavformat/asf.h
@@ -114,6 +114,7 @@ extern const ff_asf_guid ff_asf_ext_stream_audio_stream;
 extern const ff_asf_guid ff_asf_metadata_header;
 extern const ff_asf_guid ff_asf_metadata_library_header;
 extern const ff_asf_guid ff_asf_marker_header;
+extern const ff_asf_guid ff_asf_reserved_4;
 extern const ff_asf_guid ff_asf_my_guid;
 extern const ff_asf_guid ff_asf_language_guid;
 extern const ff_asf_guid ff_asf_content_encryption;