diff --git a/src/main/kotlin/net/shadowfacts/phycon/network/block/terminal/TerminalBlockEntity.kt b/src/main/kotlin/net/shadowfacts/phycon/network/block/terminal/TerminalBlockEntity.kt
index f94b8dd..6562926 100644
--- a/src/main/kotlin/net/shadowfacts/phycon/network/block/terminal/TerminalBlockEntity.kt
+++ b/src/main/kotlin/net/shadowfacts/phycon/network/block/terminal/TerminalBlockEntity.kt
@@ -36,7 +36,7 @@ class TerminalBlockEntity: DeviceBlockEntity(PhyBlockEntities.TERMINAL), Invento
 	}
 
 	private val inventoryCache = mutableMapOf<MACAddress, GroupedItemInv>()
-	val internalBuffer = BasicInventory(18)
+	val internalBuffer = TerminalBufferInventory(18)
 
 	private val pendingRequests = LinkedList<StackLocateRequest>()
 
@@ -84,7 +84,7 @@ class TerminalBlockEntity: DeviceBlockEntity(PhyBlockEntities.TERMINAL), Invento
 	}
 
 	private fun handleItemStack(packet: ItemStackPacket) {
-		val remaining = internalBuffer.insert(packet.stack)
+		val remaining = internalBuffer.insertFromNetwork(packet.stack)
 		if (!remaining.isEmpty) {
 			// todo: calculate entity spawn point by finding non-obstructed location
 			val entity = ItemEntity(world!!, pos.x.toDouble(), pos.y + 1.0, pos.z.toDouble(), remaining)
diff --git a/src/main/kotlin/net/shadowfacts/phycon/network/block/terminal/TerminalBufferInventory.kt b/src/main/kotlin/net/shadowfacts/phycon/network/block/terminal/TerminalBufferInventory.kt
new file mode 100644
index 0000000..4de16b0
--- /dev/null
+++ b/src/main/kotlin/net/shadowfacts/phycon/network/block/terminal/TerminalBufferInventory.kt
@@ -0,0 +1,59 @@
+package net.shadowfacts.phycon.network.block.terminal
+
+import alexiil.mc.lib.attributes.item.ItemStackUtil
+import net.minecraft.inventory.BasicInventory
+import net.minecraft.item.ItemStack
+import kotlin.math.min
+
+/**
+ * @author shadowfacts
+ */
+class TerminalBufferInventory(size: Int): BasicInventory(size) {
+
+	enum class Mode {
+		TO_NETWORK, FROM_NETWORK, UNASSIGNED
+	}
+
+	private val modes = Array(size) { Mode.UNASSIGNED }
+
+	fun insertFromNetwork(stack: ItemStack): ItemStack {
+		var remaining = stack.copy()
+		for (slot in 0 until invSize) {
+			if (modes[slot] == Mode.TO_NETWORK) continue
+
+			remaining = insertFromNetwork(stack, slot)
+
+			if (remaining.isEmpty) {
+				break
+			}
+		}
+		return remaining
+	}
+
+	private fun insertFromNetwork(stack: ItemStack, slot: Int): ItemStack {
+		val mode = modes[slot]
+		if (mode == Mode.TO_NETWORK) return stack
+		val current = getInvStack(slot)
+		if (current.isEmpty) {
+			setInvStack(slot, stack)
+			modes[slot] = Mode.FROM_NETWORK
+			return ItemStack.EMPTY
+		} else if (ItemStackUtil.areEqualIgnoreAmounts(stack, current)) {
+			val toTransfer = min(current.maxCount - current.count, stack.count)
+			current.count += toTransfer
+			stack.count -= toTransfer
+			modes[slot] = Mode.FROM_NETWORK
+			return stack
+		} else {
+			return stack
+		}
+	}
+
+	override fun setInvStack(slot: Int, stack: ItemStack) {
+		if (stack.isEmpty) {
+			modes[slot] = Mode.UNASSIGNED
+		}
+		super.setInvStack(slot, stack)
+	}
+
+}