diff --git a/src/main/scala/li/cil/oc/common/inventory/Inventory.scala b/src/main/scala/li/cil/oc/common/inventory/Inventory.scala
index 465bdb6fb..a7cb503f2 100644
--- a/src/main/scala/li/cil/oc/common/inventory/Inventory.scala
+++ b/src/main/scala/li/cil/oc/common/inventory/Inventory.scala
@@ -11,6 +11,8 @@ import net.minecraftforge.common.util.Constants.NBT
 trait Inventory extends IInventory {
   def items: Array[Option[ItemStack]]
 
+  def updateItems(slot: Int, stack: ItemStack) = items(slot) = Option(stack)
+
   // ----------------------------------------------------------------------- //
 
   override def getStackInSlot(slot: Int) =
@@ -45,7 +47,7 @@ trait Inventory extends IInventory {
       }
 
       val oldStack = items(slot)
-      items(slot) = None
+      updateItems(slot, null)
       if (oldStack.isDefined) {
         onItemRemoved(slot, oldStack.get)
       }
@@ -53,7 +55,7 @@ trait Inventory extends IInventory {
         if (stack.stackSize > getInventoryStackLimit) {
           stack.stackSize = getInventoryStackLimit
         }
-        items(slot) = Some(stack)
+        updateItems(slot, stack)
       }
 
       if (items(slot).isDefined) {
@@ -84,7 +86,7 @@ trait Inventory extends IInventory {
     nbt.getTagList(Settings.namespace + "items", NBT.TAG_COMPOUND).foreach((slotNbt: NBTTagCompound) => {
       val slot = slotNbt.getByte("slot")
       if (slot >= 0 && slot < items.length) {
-        items(slot) = Option(ItemUtils.loadStack(slotNbt.getCompoundTag("item")))
+        updateItems(slot, ItemUtils.loadStack(slotNbt.getCompoundTag("item")))
       }
     })
   }
diff --git a/src/main/scala/li/cil/oc/common/inventory/ItemStackInventory.scala b/src/main/scala/li/cil/oc/common/inventory/ItemStackInventory.scala
index 2c318defd..bff8b9b74 100644
--- a/src/main/scala/li/cil/oc/common/inventory/ItemStackInventory.scala
+++ b/src/main/scala/li/cil/oc/common/inventory/ItemStackInventory.scala
@@ -11,7 +11,9 @@ trait ItemStackInventory extends Inventory {
   // The item stack that provides the inventory.
   def container: ItemStack
 
-  lazy val items = Array.fill[Option[ItemStack]](getSizeInventory)(None)
+  private lazy val inventory = Array.fill[Option[ItemStack]](getSizeInventory)(None)
+
+  override def items = inventory
 
   // Initialize the list automatically if we have a container.
   if (container != null) {
@@ -24,14 +26,14 @@ trait ItemStackInventory extends Inventory {
       container.setTagCompound(new NBTTagCompound())
     }
     for (i <- 0 until items.length) {
-      items(i) = None
+      updateItems(i, null)
     }
     if (container.getTagCompound.hasKey(Settings.namespace + "items")) {
       val list = container.getTagCompound.getTagList(Settings.namespace + "items", NBT.TAG_COMPOUND)
       for (i <- 0 until (list.tagCount min items.length)) {
         val tag = list.getCompoundTagAt(i)
         if (!tag.hasNoTags) {
-          items(i) = Option(ItemUtils.loadStack(tag))
+          updateItems(i, ItemUtils.loadStack(tag))
         }
       }
     }
diff --git a/src/main/scala/li/cil/oc/common/tileentity/Assembler.scala b/src/main/scala/li/cil/oc/common/tileentity/Assembler.scala
index bce44c7bf..06abb09ef 100644
--- a/src/main/scala/li/cil/oc/common/tileentity/Assembler.scala
+++ b/src/main/scala/li/cil/oc/common/tileentity/Assembler.scala
@@ -83,7 +83,7 @@ class Assembler extends traits.Environment with traits.PowerAcceptor with traits
         requiredEnergy = totalRequiredEnergy
         ServerPacketSender.sendRobotAssembling(this, assembling = true)
 
-        for (slot <- 0 until getSizeInventory) items(slot) = None
+        for (slot <- 0 until getSizeInventory) updateItems(slot, null)
         markDirty()
 
         true
diff --git a/src/main/scala/li/cil/oc/common/tileentity/traits/Inventory.scala b/src/main/scala/li/cil/oc/common/tileentity/traits/Inventory.scala
index 8e9f9f6fc..0f606649f 100644
--- a/src/main/scala/li/cil/oc/common/tileentity/traits/Inventory.scala
+++ b/src/main/scala/li/cil/oc/common/tileentity/traits/Inventory.scala
@@ -9,7 +9,9 @@ import net.minecraft.nbt.NBTTagCompound
 import net.minecraftforge.common.util.ForgeDirection
 
 trait Inventory extends TileEntity with inventory.Inventory {
-  lazy val items = Array.fill[Option[ItemStack]](getSizeInventory)(None)
+  private lazy val inventory = Array.fill[Option[ItemStack]](getSizeInventory)(None)
+
+  def items = inventory
 
   // ----------------------------------------------------------------------- //