diff --git a/v1_10_R1/src/main/java/net/citizensnpcs/nms/v1_10_R1/entity/MobEntityController.java b/v1_10_R1/src/main/java/net/citizensnpcs/nms/v1_10_R1/entity/MobEntityController.java
index 2966f549a..1ffb11c69 100644
--- a/v1_10_R1/src/main/java/net/citizensnpcs/nms/v1_10_R1/entity/MobEntityController.java
+++ b/v1_10_R1/src/main/java/net/citizensnpcs/nms/v1_10_R1/entity/MobEntityController.java
@@ -3,14 +3,13 @@ package net.citizensnpcs.nms.v1_10_R1.entity;
 import java.lang.invoke.MethodHandle;
 import java.lang.reflect.Constructor;
 import java.util.Map;
+import java.util.WeakHashMap;
 
 import org.bukkit.Location;
 import org.bukkit.block.BlockFace;
 import org.bukkit.craftbukkit.v1_10_R1.CraftWorld;
 import org.bukkit.entity.Entity;
 
-import com.google.common.collect.Maps;
-
 import net.citizensnpcs.api.npc.NPC;
 import net.citizensnpcs.npc.AbstractEntityController;
 import net.citizensnpcs.util.NMS;
@@ -58,14 +57,14 @@ public abstract class MobEntityController extends AbstractEntityController {
         if (constructor != null)
             return constructor;
         try {
-            return clazz.getConstructor(World.class, NPC.class);
+            CONSTRUCTOR_CACHE.put(clazz, constructor = clazz.getConstructor(World.class, NPC.class));
+            return constructor;
         } catch (Exception ex) {
             throw new IllegalStateException("unable to find an entity constructor");
         }
     }
 
-    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = Maps.newHashMap();
-
+    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = new WeakHashMap<Class<?>, Constructor<?>>();
     private static final MethodHandle UUID_FIELD = NMS.getSetter(net.minecraft.server.v1_10_R1.Entity.class,
             "uniqueID");
 }
\ No newline at end of file
diff --git a/v1_11_R1/src/main/java/net/citizensnpcs/nms/v1_11_R1/entity/MobEntityController.java b/v1_11_R1/src/main/java/net/citizensnpcs/nms/v1_11_R1/entity/MobEntityController.java
index 237eb9c2a..2a7cf3d62 100644
--- a/v1_11_R1/src/main/java/net/citizensnpcs/nms/v1_11_R1/entity/MobEntityController.java
+++ b/v1_11_R1/src/main/java/net/citizensnpcs/nms/v1_11_R1/entity/MobEntityController.java
@@ -3,14 +3,13 @@ package net.citizensnpcs.nms.v1_11_R1.entity;
 import java.lang.invoke.MethodHandle;
 import java.lang.reflect.Constructor;
 import java.util.Map;
+import java.util.WeakHashMap;
 
 import org.bukkit.Location;
 import org.bukkit.block.BlockFace;
 import org.bukkit.craftbukkit.v1_11_R1.CraftWorld;
 import org.bukkit.entity.Entity;
 
-import com.google.common.collect.Maps;
-
 import net.citizensnpcs.api.npc.NPC;
 import net.citizensnpcs.npc.AbstractEntityController;
 import net.citizensnpcs.util.NMS;
@@ -58,14 +57,14 @@ public abstract class MobEntityController extends AbstractEntityController {
         if (constructor != null)
             return constructor;
         try {
-            return clazz.getConstructor(World.class, NPC.class);
+            CONSTRUCTOR_CACHE.put(clazz, constructor = clazz.getConstructor(World.class, NPC.class));
+            return constructor;
         } catch (Exception ex) {
             throw new IllegalStateException("unable to find an entity constructor");
         }
     }
 
-    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = Maps.newHashMap();
-
+    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = new WeakHashMap<Class<?>, Constructor<?>>();
     private static final MethodHandle UUID_FIELD = NMS.getSetter(net.minecraft.server.v1_11_R1.Entity.class,
             "uniqueID");
 }
\ No newline at end of file
diff --git a/v1_12_R1/src/main/java/net/citizensnpcs/nms/v1_12_R1/entity/MobEntityController.java b/v1_12_R1/src/main/java/net/citizensnpcs/nms/v1_12_R1/entity/MobEntityController.java
index 645098c8d..5c54eb546 100644
--- a/v1_12_R1/src/main/java/net/citizensnpcs/nms/v1_12_R1/entity/MobEntityController.java
+++ b/v1_12_R1/src/main/java/net/citizensnpcs/nms/v1_12_R1/entity/MobEntityController.java
@@ -3,14 +3,13 @@ package net.citizensnpcs.nms.v1_12_R1.entity;
 import java.lang.invoke.MethodHandle;
 import java.lang.reflect.Constructor;
 import java.util.Map;
+import java.util.WeakHashMap;
 
 import org.bukkit.Location;
 import org.bukkit.block.BlockFace;
 import org.bukkit.craftbukkit.v1_12_R1.CraftWorld;
 import org.bukkit.entity.Entity;
 
-import com.google.common.collect.Maps;
-
 import net.citizensnpcs.api.npc.NPC;
 import net.citizensnpcs.npc.AbstractEntityController;
 import net.citizensnpcs.util.NMS;
@@ -59,13 +58,14 @@ public abstract class MobEntityController extends AbstractEntityController {
         if (constructor != null)
             return constructor;
         try {
-            return clazz.getConstructor(World.class, NPC.class);
+            CONSTRUCTOR_CACHE.put(clazz, constructor = clazz.getConstructor(World.class, NPC.class));
+            return constructor;
         } catch (Exception ex) {
             throw new IllegalStateException("unable to find an entity constructor");
         }
     }
 
-    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = Maps.newHashMap();
+    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = new WeakHashMap<Class<?>, Constructor<?>>();
     private static final MethodHandle UUID_FIELD = NMS.getSetter(net.minecraft.server.v1_12_R1.Entity.class,
             "uniqueID");
 }
\ No newline at end of file
diff --git a/v1_13_R2/src/main/java/net/citizensnpcs/nms/v1_13_R2/entity/MobEntityController.java b/v1_13_R2/src/main/java/net/citizensnpcs/nms/v1_13_R2/entity/MobEntityController.java
index 85b52b2d2..2a9376465 100644
--- a/v1_13_R2/src/main/java/net/citizensnpcs/nms/v1_13_R2/entity/MobEntityController.java
+++ b/v1_13_R2/src/main/java/net/citizensnpcs/nms/v1_13_R2/entity/MobEntityController.java
@@ -3,14 +3,13 @@ package net.citizensnpcs.nms.v1_13_R2.entity;
 import java.lang.invoke.MethodHandle;
 import java.lang.reflect.Constructor;
 import java.util.Map;
+import java.util.WeakHashMap;
 
 import org.bukkit.Location;
 import org.bukkit.block.BlockFace;
 import org.bukkit.craftbukkit.v1_13_R2.CraftWorld;
 import org.bukkit.entity.Entity;
 
-import com.google.common.collect.Maps;
-
 import net.citizensnpcs.api.npc.NPC;
 import net.citizensnpcs.npc.AbstractEntityController;
 import net.citizensnpcs.util.NMS;
@@ -58,14 +57,14 @@ public abstract class MobEntityController extends AbstractEntityController {
         if (constructor != null)
             return constructor;
         try {
-            return clazz.getConstructor(World.class, NPC.class);
+            CONSTRUCTOR_CACHE.put(clazz, constructor = clazz.getConstructor(World.class, NPC.class));
+            return constructor;
         } catch (Exception ex) {
             throw new IllegalStateException("unable to find an entity constructor");
         }
     }
 
-    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = Maps.newHashMap();
-
+    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = new WeakHashMap<Class<?>, Constructor<?>>();
     private static final MethodHandle UUID_FIELD = NMS.getSetter(net.minecraft.server.v1_13_R2.Entity.class,
             "uniqueID");
 }
\ No newline at end of file
diff --git a/v1_14_R1/src/main/java/net/citizensnpcs/nms/v1_14_R1/entity/MobEntityController.java b/v1_14_R1/src/main/java/net/citizensnpcs/nms/v1_14_R1/entity/MobEntityController.java
index 850c1a357..df2968c8a 100644
--- a/v1_14_R1/src/main/java/net/citizensnpcs/nms/v1_14_R1/entity/MobEntityController.java
+++ b/v1_14_R1/src/main/java/net/citizensnpcs/nms/v1_14_R1/entity/MobEntityController.java
@@ -3,14 +3,13 @@ package net.citizensnpcs.nms.v1_14_R1.entity;
 import java.lang.invoke.MethodHandle;
 import java.lang.reflect.Constructor;
 import java.util.Map;
+import java.util.WeakHashMap;
 
 import org.bukkit.Location;
 import org.bukkit.block.BlockFace;
 import org.bukkit.craftbukkit.v1_14_R1.CraftWorld;
 import org.bukkit.entity.Entity;
 
-import com.google.common.collect.Maps;
-
 import net.citizensnpcs.api.npc.NPC;
 import net.citizensnpcs.nms.v1_14_R1.util.NMSImpl;
 import net.citizensnpcs.npc.AbstractEntityController;
@@ -63,14 +62,14 @@ public abstract class MobEntityController extends AbstractEntityController {
         if (constructor != null)
             return constructor;
         try {
-            return clazz.getConstructor(EntityTypes.class, World.class, NPC.class);
+            CONSTRUCTOR_CACHE.put(clazz, constructor = clazz.getConstructor(EntityTypes.class, World.class, NPC.class));
+            return constructor;
         } catch (Exception ex) {
             throw new IllegalStateException("unable to find an entity constructor");
         }
     }
 
-    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = Maps.newHashMap();
-
+    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = new WeakHashMap<Class<?>, Constructor<?>>();
     private static final MethodHandle UUID_FIELD = NMS.getSetter(net.minecraft.server.v1_14_R1.Entity.class,
             "uniqueID");
 }
\ No newline at end of file
diff --git a/v1_15_R1/src/main/java/net/citizensnpcs/nms/v1_15_R1/entity/MobEntityController.java b/v1_15_R1/src/main/java/net/citizensnpcs/nms/v1_15_R1/entity/MobEntityController.java
index 658a9b58b..d34d30c33 100644
--- a/v1_15_R1/src/main/java/net/citizensnpcs/nms/v1_15_R1/entity/MobEntityController.java
+++ b/v1_15_R1/src/main/java/net/citizensnpcs/nms/v1_15_R1/entity/MobEntityController.java
@@ -3,14 +3,13 @@ package net.citizensnpcs.nms.v1_15_R1.entity;
 import java.lang.invoke.MethodHandle;
 import java.lang.reflect.Constructor;
 import java.util.Map;
+import java.util.WeakHashMap;
 
 import org.bukkit.Location;
 import org.bukkit.block.BlockFace;
 import org.bukkit.craftbukkit.v1_15_R1.CraftWorld;
 import org.bukkit.entity.Entity;
 
-import com.google.common.collect.Maps;
-
 import net.citizensnpcs.api.npc.NPC;
 import net.citizensnpcs.nms.v1_15_R1.util.NMSImpl;
 import net.citizensnpcs.npc.AbstractEntityController;
@@ -63,14 +62,14 @@ public abstract class MobEntityController extends AbstractEntityController {
         if (constructor != null)
             return constructor;
         try {
-            return clazz.getConstructor(EntityTypes.class, World.class, NPC.class);
+            CONSTRUCTOR_CACHE.put(clazz, constructor = clazz.getConstructor(EntityTypes.class, World.class, NPC.class));
+            return constructor;
         } catch (Exception ex) {
             throw new IllegalStateException("unable to find an entity constructor");
         }
     }
 
-    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = Maps.newHashMap();
-
+    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = new WeakHashMap<Class<?>, Constructor<?>>();
     private static final MethodHandle UUID_FIELD = NMS.getSetter(net.minecraft.server.v1_15_R1.Entity.class,
             "uniqueID");
 }
\ No newline at end of file
diff --git a/v1_16_R3/src/main/java/net/citizensnpcs/nms/v1_16_R3/entity/MobEntityController.java b/v1_16_R3/src/main/java/net/citizensnpcs/nms/v1_16_R3/entity/MobEntityController.java
index f018b6616..e2eaf1d95 100644
--- a/v1_16_R3/src/main/java/net/citizensnpcs/nms/v1_16_R3/entity/MobEntityController.java
+++ b/v1_16_R3/src/main/java/net/citizensnpcs/nms/v1_16_R3/entity/MobEntityController.java
@@ -3,14 +3,13 @@ package net.citizensnpcs.nms.v1_16_R3.entity;
 import java.lang.invoke.MethodHandle;
 import java.lang.reflect.Constructor;
 import java.util.Map;
+import java.util.WeakHashMap;
 
 import org.bukkit.Location;
 import org.bukkit.block.BlockFace;
 import org.bukkit.craftbukkit.v1_16_R3.CraftWorld;
 import org.bukkit.entity.Entity;
 
-import com.google.common.collect.Maps;
-
 import net.citizensnpcs.api.npc.NPC;
 import net.citizensnpcs.nms.v1_16_R3.util.NMSImpl;
 import net.citizensnpcs.npc.AbstractEntityController;
@@ -63,13 +62,14 @@ public abstract class MobEntityController extends AbstractEntityController {
         if (constructor != null)
             return constructor;
         try {
-            return clazz.getConstructor(EntityTypes.class, World.class, NPC.class);
+            CONSTRUCTOR_CACHE.put(clazz, constructor = clazz.getConstructor(EntityTypes.class, World.class, NPC.class));
+            return constructor;
         } catch (Exception ex) {
             throw new IllegalStateException("unable to find an entity constructor");
         }
     }
 
-    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = Maps.newHashMap();
+    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = new WeakHashMap<Class<?>, Constructor<?>>();
     private static final MethodHandle UUID_FIELD = NMS.getSetter(net.minecraft.server.v1_16_R3.Entity.class,
             "uniqueID");
 }
\ No newline at end of file
diff --git a/v1_17_R1/src/main/java/net/citizensnpcs/nms/v1_17_R1/entity/MobEntityController.java b/v1_17_R1/src/main/java/net/citizensnpcs/nms/v1_17_R1/entity/MobEntityController.java
index 49a869ebf..bdfff3e87 100644
--- a/v1_17_R1/src/main/java/net/citizensnpcs/nms/v1_17_R1/entity/MobEntityController.java
+++ b/v1_17_R1/src/main/java/net/citizensnpcs/nms/v1_17_R1/entity/MobEntityController.java
@@ -2,14 +2,13 @@ package net.citizensnpcs.nms.v1_17_R1.entity;
 
 import java.lang.reflect.Constructor;
 import java.util.Map;
+import java.util.WeakHashMap;
 
 import org.bukkit.Location;
 import org.bukkit.block.BlockFace;
 import org.bukkit.craftbukkit.v1_17_R1.CraftWorld;
 import org.bukkit.entity.Entity;
 
-import com.google.common.collect.Maps;
-
 import net.citizensnpcs.api.npc.NPC;
 import net.citizensnpcs.nms.v1_17_R1.util.NMSImpl;
 import net.citizensnpcs.npc.AbstractEntityController;
@@ -57,11 +56,12 @@ public abstract class MobEntityController extends AbstractEntityController {
         if (constructor != null)
             return constructor;
         try {
-            return clazz.getConstructor(EntityType.class, Level.class, NPC.class);
+            CONSTRUCTOR_CACHE.put(clazz, constructor = clazz.getConstructor(EntityType.class, Level.class, NPC.class));
+            return constructor;
         } catch (Exception ex) {
             throw new IllegalStateException("unable to find an entity constructor");
         }
     }
 
-    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = Maps.newHashMap();
+    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = new WeakHashMap<Class<?>, Constructor<?>>();
 }
\ No newline at end of file
diff --git a/v1_18_R1/src/main/java/net/citizensnpcs/nms/v1_18_R1/entity/MobEntityController.java b/v1_18_R1/src/main/java/net/citizensnpcs/nms/v1_18_R1/entity/MobEntityController.java
index 2a5551a2c..4efbeacb2 100644
--- a/v1_18_R1/src/main/java/net/citizensnpcs/nms/v1_18_R1/entity/MobEntityController.java
+++ b/v1_18_R1/src/main/java/net/citizensnpcs/nms/v1_18_R1/entity/MobEntityController.java
@@ -2,14 +2,13 @@ package net.citizensnpcs.nms.v1_18_R1.entity;
 
 import java.lang.reflect.Constructor;
 import java.util.Map;
+import java.util.WeakHashMap;
 
 import org.bukkit.Location;
 import org.bukkit.block.BlockFace;
 import org.bukkit.craftbukkit.v1_18_R1.CraftWorld;
 import org.bukkit.entity.Entity;
 
-import com.google.common.collect.Maps;
-
 import net.citizensnpcs.api.npc.NPC;
 import net.citizensnpcs.nms.v1_18_R1.util.NMSImpl;
 import net.citizensnpcs.npc.AbstractEntityController;
@@ -57,11 +56,12 @@ public abstract class MobEntityController extends AbstractEntityController {
         if (constructor != null)
             return constructor;
         try {
-            return clazz.getConstructor(EntityType.class, Level.class, NPC.class);
+            CONSTRUCTOR_CACHE.put(clazz, constructor = clazz.getConstructor(EntityType.class, Level.class, NPC.class));
+            return constructor;
         } catch (Exception ex) {
             throw new IllegalStateException("unable to find an entity constructor");
         }
     }
 
-    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = Maps.newHashMap();
+    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = new WeakHashMap<Class<?>, Constructor<?>>();
 }
\ No newline at end of file
diff --git a/v1_8_R3/src/main/java/net/citizensnpcs/nms/v1_8_R3/entity/MobEntityController.java b/v1_8_R3/src/main/java/net/citizensnpcs/nms/v1_8_R3/entity/MobEntityController.java
index 9ebc761ad..78ef5d4bd 100644
--- a/v1_8_R3/src/main/java/net/citizensnpcs/nms/v1_8_R3/entity/MobEntityController.java
+++ b/v1_8_R3/src/main/java/net/citizensnpcs/nms/v1_8_R3/entity/MobEntityController.java
@@ -3,14 +3,13 @@ package net.citizensnpcs.nms.v1_8_R3.entity;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Field;
 import java.util.Map;
+import java.util.WeakHashMap;
 
 import org.bukkit.Location;
 import org.bukkit.block.BlockFace;
 import org.bukkit.craftbukkit.v1_8_R3.CraftWorld;
 import org.bukkit.entity.Entity;
 
-import com.google.common.collect.Maps;
-
 import net.citizensnpcs.api.npc.NPC;
 import net.citizensnpcs.npc.AbstractEntityController;
 import net.citizensnpcs.util.NMS;
@@ -58,12 +57,13 @@ public abstract class MobEntityController extends AbstractEntityController {
         if (constructor != null)
             return constructor;
         try {
-            return clazz.getConstructor(World.class, NPC.class);
+            CONSTRUCTOR_CACHE.put(clazz, constructor = clazz.getConstructor(World.class, NPC.class));
+            return constructor;
         } catch (Exception ex) {
             throw new IllegalStateException("unable to find an entity constructor");
         }
     }
 
-    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = Maps.newHashMap();
+    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE = new WeakHashMap<Class<?>, Constructor<?>>();
     private static final Field UUID_FIELD = NMS.getField(net.minecraft.server.v1_8_R3.Entity.class, "uniqueID");
 }
\ No newline at end of file