diff --git a/modules/demux/asf/libasf_guid.h b/modules/demux/asf/libasf_guid.h
index a99a377969640ea54f23ee771698b53a0f765cfd..7f2935cdb21484869fb5623681cc3c9d640f8121 100644
--- a/modules/demux/asf/libasf_guid.h
+++ b/modules/demux/asf/libasf_guid.h
@@ -30,7 +30,7 @@
  *****************************************************************************/
 #define GUID_FMT "0x%x-0x%x-0x%x-0x%2.2x%2.2x%2.2x%2.2x%2.2x%2.2x%2.2x%2.2x"
 #define GUID_PRINT( guid )  \
-    (guid).Data1,              \
+    (unsigned)(guid).Data1,              \
     (guid).Data2,              \
     (guid).Data3,              \
     (guid).Data4[0],(guid).Data4[1],(guid).Data4[2],(guid).Data4[3],    \