diff --git a/gradle.properties b/gradle.properties
index 8d179d80..90a6b576 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -8,6 +8,6 @@ loader_version=0.10.8
 fabric_version=0.31.0+1.16
 fabric_asm_version=v2.2
 
-mod_version = 1.10.1
+mod_version = 1.10.2
 maven_group = me.modmuss50
 archives_base_name = optifabric
diff --git a/src/main/java/me/modmuss50/optifabric/mod/OptifineSetup.java b/src/main/java/me/modmuss50/optifabric/mod/OptifineSetup.java
index 1063cffc..b6f4ca20 100644
--- a/src/main/java/me/modmuss50/optifabric/mod/OptifineSetup.java
+++ b/src/main/java/me/modmuss50/optifabric/mod/OptifineSetup.java
@@ -209,8 +209,10 @@ private static IMappingProvider createMappings(String from, String to) {
 		});
 
 		ClassDef clientEntityHandler = nameToClass.get("net/minecraft/class_638$class_5612");
-		ClassDef clientWorld = nameToClass.get("net/minecraft/class_638");
-		extraFields.put(new Member(clientEntityHandler.getName(from), "this$0", 'L' + clientWorld.getName(from) + ';'), "field_27735");
+		if (clientEntityHandler != null) {//Only present in 1.17.x (20w45a+)
+			ClassDef clientWorld = nameToClass.get("net/minecraft/class_638");
+			extraFields.put(new Member(clientEntityHandler.getName(from), "this$0", 'L' + clientWorld.getName(from) + ';'), "field_27735");
+		}
 
 		//In dev
 		if (FabricLoader.getInstance().isDevelopmentEnvironment()) {