diff --git a/src/main/java/ru/bclib/api/biomes/SurfaceMaterialProvider.java b/src/main/java/ru/bclib/interfaces/SurfaceMaterialProvider.java
similarity index 87%
rename from src/main/java/ru/bclib/api/biomes/SurfaceMaterialProvider.java
rename to src/main/java/ru/bclib/interfaces/SurfaceMaterialProvider.java
index fc0ac1e8..a7584b19 100644
--- a/src/main/java/ru/bclib/api/biomes/SurfaceMaterialProvider.java
+++ b/src/main/java/ru/bclib/interfaces/SurfaceMaterialProvider.java
@@ -1,4 +1,4 @@
-package ru.bclib.api.biomes;
+package ru.bclib.interfaces;
 
 import net.minecraft.world.level.block.state.BlockState;
 
diff --git a/src/main/java/ru/bclib/world/generator/map/square/SquareBiomeMap.java b/src/main/java/ru/bclib/world/generator/map/square/SquareBiomeMap.java
index 6c523db8..d5322705 100644
--- a/src/main/java/ru/bclib/world/generator/map/square/SquareBiomeMap.java
+++ b/src/main/java/ru/bclib/world/generator/map/square/SquareBiomeMap.java
@@ -103,8 +103,10 @@ public class SquareBiomeMap implements BiomeMap {
 		ChunkPos cpos = new ChunkPos(MHelper.floor(x / SquareBiomeChunk.WIDTH), MHelper.floor(z / SquareBiomeChunk.WIDTH));
 		SquareBiomeChunk chunk = maps.get(cpos);
 		if (chunk == null) {
-			random.setLargeFeatureWithSalt(0, cpos.x, cpos.z, 0);
-			chunk = new SquareBiomeChunk(random, picker);
+			synchronized (random) {
+				random.setLargeFeatureWithSalt(0, cpos.x, cpos.z, 0);
+				chunk = new SquareBiomeChunk(random, picker);
+			}
 			maps.put(cpos, chunk);
 		}