diff --git a/Build/Configurations/Srb2-21slopeszb.cfg b/Build/Configurations/Srb2-21slopeszb.cfg
index 75c35b3..d098cc4 100644
--- a/Build/Configurations/Srb2-21slopeszb.cfg
+++ b/Build/Configurations/Srb2-21slopeszb.cfg
@@ -37,6 +37,32 @@ linetagindicatesectors = true;
 // The format interface handles the map data format - DoomMapSetIO for SRB2DB2, SRB2MapSetIO for Zone Builder
 formatinterface = "SRB2MapSetIO";
 
+//Sky textures for vanilla maps
+defaultskytextures
+{
+	SKY1 = "MAP01,MAP02,MAP03,MAP50,MAPA1,MAPA2,MAPA5,MAPA6,MAPA9,MAPAA,MAPAB,MAPAC,MAPAD,MAPAE,MAPAG,MAPAJ,MAPAK,MAPF0,MAPF1,MAPFA,MAPM0,MAPM8,MAPMA,MAPMB,MAPMC";
+	SKY4 = "MAP04,MAP06,MAP51,MAPF8,MAPM1";
+	SKY6 = "MAP05";
+	SKY7 = "MAP07,MAP08,MAP09,MAP52,MAPM2,MAPM5";
+	SKY10 = "MAP12,MAP53,MAPM3";
+	SKY11 = "MAP10,MAP11,MAP16,MAP55,MAPF2,MAPF5,MAPF6,MAPF9,MAPM7";
+	SKY13 = "MAP13,MAP54,MAPAS";
+	SKY21 = "MAPAF,MAPF7,MAPM4";
+	SKY22 = "MAP22,MAP23,MAP24,MAP25,MAP56,MAPAN,MAPAO,MAPF4,MAPM6";
+	SKY29 = "MAP58,MAPAV";
+	SKY30 = "MAP30";
+	SKY35 = "MAP41";
+	SKY40 = "MAP40";
+	SKY55 = "MAPF3,MAPM9";
+	SKY66 = "MAPAT";
+	SKY99 = "MAP57";
+	SKY103 = "MAPA3,MAPA4,MAPAU";
+	SKY107 = "MAPA7,MAPA8";
+	SKY117 = "MAPAH,MAPAI";
+	SKY127 = "MAPAR";
+	SKY132 = "MAPAW";
+}
+
 // Default lump name for new map
 defaultlumpname = "MAP01";