diff --git a/zdefs.acs b/zdefs.acs
index 6cda44c..d75cd53 100644
--- a/zdefs.acs
+++ b/zdefs.acs
@@ -24,6 +24,11 @@
 #define TEXTURE_MIDDLE          1
 #define TEXTURE_BOTTOM          2
 
+// same information as combinable bit flags
+#define TEXFLAG_TOP				1
+#define TEXFLAG_MIDDLE			2
+#define TEXFLAG_BOTTOM			4
+
 #define GAME_SINGLE_PLAYER      0
 #define GAME_NET_COOPERATIVE    1
 #define GAME_NET_DEATHMATCH     2
@@ -601,3 +606,6 @@
 #define CHANGELEVEL_NOMONSTERS 4
 #define CHANGELEVEL_CHANGESKILL 8
 #define CHANGELEVEL_NOINTERMISSION 16
+
+#define NO_CHANGE -32767.0
+
diff --git a/zspecial.acs b/zspecial.acs
index 109de55..4fc58d5 100644
--- a/zspecial.acs
+++ b/zspecial.acs
@@ -101,6 +101,7 @@ special
 	 49:GlassBreak(0,1),
 	 51:Sector_SetLink(4),
 	 52:Scroll_Wall(5),
+	 53:Line_SetTextureOffset(5),
 	 76:TeleportOther(3),
 	 77:TeleportGroup(5),
 	 78:TeleportInSector(4,5),