diff --git a/src/main/java/com/volmit/iris/pregen/DirectWorldWriter.java b/src/main/java/com/volmit/iris/pregen/DirectWorldWriter.java
index cd50909c2..79c69a795 100644
--- a/src/main/java/com/volmit/iris/pregen/DirectWorldWriter.java
+++ b/src/main/java/com/volmit/iris/pregen/DirectWorldWriter.java
@@ -242,7 +242,9 @@ public class DirectWorldWriter {
 
         for(Biome biome : Biome.values())
         {
-            biomeIds.put(biome, INMS.get().getBiomeId(biome));
+            if (!biome.name().equals("CUSTOM")) {
+                biomeIds.put(biome, INMS.get().getBiomeId(biome));
+            }
         }
 
         return biomeIds;