diff --git a/modules/demux/mkv/mkv.hpp b/modules/demux/mkv/mkv.hpp
index 38a62aa2af2ca8462eedfda25608543d1bd9eec6..fa9a1e81a5994a487ec846fed6d8c9a2cec3139e 100644
--- a/modules/demux/mkv/mkv.hpp
+++ b/modules/demux/mkv/mkv.hpp
@@ -113,7 +113,7 @@ enum
 
 #define MKVD_TIMECODESCALE 1000000
 
-#define MKV_IS_ID( el, C ) ( el != NULL && (el->operator const EbmlId&()) == (C::ClassInfos.ClassId()) )
+#define MKV_IS_ID( el, C ) ( el != NULL && (el->operator const EbmlId&()) == (C::ClassInfos.ClassId()) && !el->IsDummy() )
 #define MKV_CHECKED_PTR_DECL( name, type, src ) type * name = MKV_IS_ID(src, type) ? static_cast<type*>(src) : NULL
 #define MKV_CHECKED_PTR_DECL_CONST( name, type, src ) const type * name = MKV_IS_ID(src, type) ? static_cast<const type*>(src) : NULL