--- a/net/minecraft/entity/ai/brain/schedule/Activity.java
+++ b/net/minecraft/entity/ai/brain/schedule/Activity.java
@@ -2,7 +2,7 @@
 
 import net.minecraft.util.registry.Registry;
 
-public class Activity {
+public class Activity extends net.minecraftforge.registries.ForgeRegistryEntry<Activity> {
    public static final Activity field_221365_a = func_221363_a("core");
    public static final Activity field_221366_b = func_221363_a("idle");
    public static final Activity field_221367_c = func_221363_a("work");
