diff --git a/build.gradle b/build.gradle
index 04b9099d9c..71c590d2f1 100644
--- a/build.gradle
+++ b/build.gradle
@@ -27,7 +27,7 @@ plugins {
 	id 'net.fabricmc.filament' version '0.3.0'
 }
 
-def minecraft_version = "1.18-pre3"
+def minecraft_version = "1.18-pre4"
 
 def ENV = System.getenv()
 // Fetch build number from Github Actions
diff --git a/mappings/net/minecraft/world/biome/source/BiomeSource.mapping b/mappings/net/minecraft/world/biome/source/BiomeSource.mapping
index 46b333af5d..0431dffbf6 100644
--- a/mappings/net/minecraft/world/biome/source/BiomeSource.mapping
+++ b/mappings/net/minecraft/world/biome/source/BiomeSource.mapping
@@ -1,5 +1,5 @@
 CLASS net/minecraft/class_1966 net/minecraft/world/biome/source/BiomeSource
-	FIELD field_20643 biomes Ljava/util/List;
+	FIELD field_20643 biomes Ljava/util/Set;
 	FIELD field_24713 CODEC Lcom/mojang/serialization/Codec;
 	METHOD method_24385 locateBiome (IIIIILjava/util/function/Predicate;Ljava/util/Random;ZLnet/minecraft/class_6544$class_6552;)Lnet/minecraft/class_2338;
 		ARG 1 x
@@ -12,7 +12,7 @@ CLASS net/minecraft/class_1966 net/minecraft/world/biome/source/BiomeSource
 	METHOD method_27985 withSeed (J)Lnet/minecraft/class_1966;
 		ARG 1 seed
 	METHOD method_28442 getCodec ()Lcom/mojang/serialization/Codec;
-	METHOD method_28443 getBiomes ()Ljava/util/List;
+	METHOD method_28443 getBiomes ()Ljava/util/Set;
 	METHOD method_38114 addDebugInfo (Ljava/util/List;Lnet/minecraft/class_2338;Lnet/minecraft/class_6544$class_6552;)V
 		ARG 1 info
 		ARG 2 pos