diff --git a/src/lua_maplib.c b/src/lua_maplib.c
index a90b83c99..144a6b3f1 100644
--- a/src/lua_maplib.c
+++ b/src/lua_maplib.c
@@ -139,6 +139,7 @@ static const char *const side_opt[] = {
 	"toptexture",
 	"bottomtexture",
 	"midtexture",
+	"line",
 	"sector",
 	"special",
 	"repeatcnt",