diff --git a/src/matroska.h b/src/matroska.h
index 5de37ec74..41b35a94b 100644
--- a/src/matroska.h
+++ b/src/matroska.h
@@ -59,5 +59,6 @@
 #define MKV_S_TEXTASS    "S_TEXT/ASS"
 #define MKV_S_TEXTUSF    "S_TEXT/USF"
 #define MKV_S_VOBSUB     "S_VOBSUB"
+#define MKV_S_VOBSUBZLIB "S_VOBSUB/ZLIB"
 
 #endif // __MATROSKA_H