diff --git a/InventoryAccess/1_14_R1/src/main/java/de/studiocode/inventoryaccess/v1_14_R1/util/InventoryUtilsImpl.java b/InventoryAccess/1_14_R1/src/main/java/de/studiocode/inventoryaccess/v1_14_R1/util/InventoryUtilsImpl.java
index 927c478..a05b491 100644
--- a/InventoryAccess/1_14_R1/src/main/java/de/studiocode/inventoryaccess/v1_14_R1/util/InventoryUtilsImpl.java
+++ b/InventoryAccess/1_14_R1/src/main/java/de/studiocode/inventoryaccess/v1_14_R1/util/InventoryUtilsImpl.java
@@ -8,6 +8,7 @@ import org.bukkit.craftbukkit.v1_14_R1.entity.CraftHumanEntity;
 import org.bukkit.craftbukkit.v1_14_R1.entity.CraftPlayer;
 import org.bukkit.craftbukkit.v1_14_R1.inventory.CraftContainer;
 import org.bukkit.entity.Player;
+import org.bukkit.event.inventory.InventoryType;
 import org.bukkit.inventory.Inventory;
 
 import java.lang.reflect.Method;
@@ -20,8 +21,30 @@ public class InventoryUtilsImpl implements InventoryUtils {
     @Override
     public void openCustomInventory(Player player, Inventory inventory) {
         EntityPlayer entityPlayer = ((CraftPlayer) player).getHandle();
-        Containers<?> windowType = CraftContainer.getNotchInventoryType(inventory.getType());
+        Containers<?> windowType = getNotchInventoryType(inventory);
         ReflectionUtils.invokeMethod(OPEN_CUSTOM_INVENTORY_METHOD, player, inventory, entityPlayer, windowType);
     }
     
+    private static Containers<?> getNotchInventoryType(Inventory inventory) {
+        InventoryType type = inventory.getType();
+        if (type == InventoryType.CHEST) {
+            switch (inventory.getSize()) {
+                case 9:
+                    return Containers.GENERIC_9X1;
+                case 18:
+                    return Containers.GENERIC_9X2;
+                case 27:
+                    return Containers.GENERIC_9X3;
+                case 36:
+                    return Containers.GENERIC_9X4;
+                case 45:
+                    return Containers.GENERIC_9X5;
+                case 54:
+                    return Containers.GENERIC_9X6;
+                default:
+                    throw new IllegalArgumentException("Unsupported custom inventory size " + inventory.getSize());
+            }
+        } else return CraftContainer.getNotchInventoryType(type);
+    }
+    
 }