diff --git a/src/main/java/codechicken/nei/ClientHandler.java b/src/main/java/codechicken/nei/ClientHandler.java
index e8a17444..9b87bc21 100644
--- a/src/main/java/codechicken/nei/ClientHandler.java
+++ b/src/main/java/codechicken/nei/ClientHandler.java
@@ -299,6 +299,10 @@ public class ClientHandler
                 lastworld = null;
             else if (gui instanceof GuiSelectWorld)
                 NEIClientConfig.reloadSaves();
+            else if(gui == null) {
+                /* prevent WorldClient reference being held in the Gui */
+                NEIController.manager = null;
+            }
         }
         lastGui = gui;
     }
@@ -328,6 +332,8 @@ public class ClientHandler
 
                 if (!Minecraft.getMinecraft().isSingleplayer())//wait for server to initiate in singleplayer
                     NEIClientConfig.loadWorld("remote/" + ClientUtils.getServerIP().replace(':', '~'));
+
+                ItemMobSpawner.clearEntityReferences(world);
             }
 
             lastworld = world;
diff --git a/src/main/java/codechicken/nei/ItemMobSpawner.java b/src/main/java/codechicken/nei/ItemMobSpawner.java
index 43ccf406..87f028aa 100644
--- a/src/main/java/codechicken/nei/ItemMobSpawner.java
+++ b/src/main/java/codechicken/nei/ItemMobSpawner.java
@@ -96,6 +96,10 @@ public class ItemMobSpawner extends ItemBlock
         return e;
     }
 
+    public static void clearEntityReferences(World newWorld) {
+        entityHashMap.values().removeIf(e -> e.worldObj != newWorld);
+    }
+
     private void setDefaultTag(ItemStack itemstack) {
         if (!IDtoNameMap.containsKey(itemstack.getItemDamage()))
             itemstack.setItemDamage(idPig);