diff --git a/src/main/java/ru/bclib/api/biomes/SurfaceMaterialProvider.java b/src/main/java/ru/bclib/api/biomes/SurfaceMaterialProvider.java
index a4abbdf7..fc0ac1e8 100644
--- a/src/main/java/ru/bclib/api/biomes/SurfaceMaterialProvider.java
+++ b/src/main/java/ru/bclib/api/biomes/SurfaceMaterialProvider.java
@@ -4,5 +4,6 @@ import net.minecraft.world.level.block.state.BlockState;
 
 public interface SurfaceMaterialProvider {
     BlockState getTopMaterial();
+    BlockState getUnderMaterial();
     BlockState getAltTopMaterial();
 }