diff --git a/server/inventories/ItemStack.ts b/server/inventories/ItemStack.ts
index f698a39..e67e254 100644
--- a/server/inventories/ItemStack.ts
+++ b/server/inventories/ItemStack.ts
@@ -92,18 +92,19 @@ export class ItemStack {
 	public insert(itemStack:ItemStack) {
 		const remainingSpace = this.spaceAvaliable;
 		if (remainingSpace === 0) {
-			return;
+			return false;
 		}
 
 		if (remainingSpace >= itemStack.size) {
 			this.size += itemStack.size;
 			itemStack.size = 0;
-			return;
+			return true;
 		}
 
 		if (remainingSpace < itemStack.size) {
 			this.size += remainingSpace;
 			itemStack.size -= remainingSpace;
+			return true;
 		}
 	}
 
diff --git a/server/inventories/PlayerInventory.ts b/server/inventories/PlayerInventory.ts
index a842da6..e43ce2a 100644
--- a/server/inventories/PlayerInventory.ts
+++ b/server/inventories/PlayerInventory.ts
@@ -1,4 +1,6 @@
 import { Player } from "../entities/Player";
+import { PacketSetSlot } from "../packets/SetSlot";
+import { PacketWindowItems } from "../packets/WindowItems";
 import { Inventory } from "./Inventory";
 import { ItemStack } from "./ItemStack";
 
@@ -11,64 +13,95 @@ export default class PlayerInventory extends Inventory {
 		this.player = player;
 	}
 
+	sendUpdatedStacks(stackIdsChanged:Array<number>) {
+		let updateBuffer = Buffer.alloc(0);
+		for (const slotId of stackIdsChanged) {
+			const slotItem = this.itemStacks[slotId];
+			let buffer:Buffer;
+			if (slotItem == null) {
+				buffer = new PacketSetSlot(0, slotId, -1).writeData();
+			} else {
+				buffer = new PacketSetSlot(0, slotId, slotItem.itemID, slotItem.size, slotItem.damage).writeData();
+			}
+
+			updateBuffer = Buffer.concat([updateBuffer, buffer], updateBuffer.length + buffer.length);
+		}
+		if (updateBuffer.length > 0) {
+			this.player.mpClient?.send(updateBuffer);
+		}
+	}
+
 	addItemStack(itemStack:ItemStack) {
 		const itemStacksOfSameType:Array<ItemStack> = new Array<ItemStack>();
+		const itemStackIds:Array<number> = new Array<number>();
+		const stackIdsChanged:Array<number> = new Array<number>();
 
 		// Check bottom inventory row (hotbar) first.
 		let workingItemStack:ItemStack | null;
 		for (let slotId = 36; slotId <= 44; slotId++) {
 			if ((workingItemStack = this.itemStacks[slotId]) != null) {
 				itemStacksOfSameType.push(workingItemStack);
+				itemStackIds.push(slotId);
 			}
 		}
 
 		for (let slotId = 9; slotId <= 35; slotId++) {
 			if ((workingItemStack = this.itemStacks[slotId]) != null) {
 				itemStacksOfSameType.push(workingItemStack);
+				itemStackIds.push(slotId);
 			}
 		}
 
 		// Insert into existing stacks first.
-		for (const inventoryItemStack of itemStacksOfSameType) {
+		for (let i = 0; i < itemStacksOfSameType.length; i++) {
+			const inventoryItemStack = itemStacksOfSameType[i];
 			// Exit early if we have nothing left
 			if (itemStack.size === 0) {
-				return;
+				return this.sendUpdatedStacks(stackIdsChanged);
 			}
 
 			if (inventoryItemStack.itemID !== itemStack.itemID || inventoryItemStack.damage !== itemStack.damage) {
 				continue;
 			}
 
-			inventoryItemStack.insert(itemStack);
+			if (inventoryItemStack.insert(itemStack)) {
+				stackIdsChanged.push(itemStackIds[i]);
+			}
 		}
 
 		// Exit early if we have nothing left
 		if (itemStack.size === 0) {
-			return;
+			return this.sendUpdatedStacks(stackIdsChanged);
 		}
 
 		for (let slotId = 36; slotId <= 44; slotId++) {
 			// Exit early if we have nothing left
 			if (itemStack.size === 0) {
-				return;
+				return this.sendUpdatedStacks(stackIdsChanged);
 			}
 
 			if ((workingItemStack = this.itemStacks[slotId]) == null) {
 				const stack = this.itemStacks[slotId] = new ItemStack(itemStack.itemID, 0, itemStack.damage);
-				stack.insert(itemStack);
+				if (stack.insert(itemStack)) {
+					stackIdsChanged.push(slotId);
+				}
 			}
 		}
 
 		for (let slotId = 9; slotId <= 35; slotId++) {
 			// Exit early if we have nothing left
 			if (itemStack.size === 0) {
-				return;
+				return this.sendUpdatedStacks(stackIdsChanged);
 			}
 
 			if ((workingItemStack = this.itemStacks[slotId]) == null) {
 				const stack = this.itemStacks[slotId] = new ItemStack(itemStack.itemID, 0, itemStack.damage);
-				stack.insert(itemStack);
+				if (stack.insert(itemStack)) {
+					stackIdsChanged.push(slotId);
+				}
 			}
 		}
+
+		this.sendUpdatedStacks(stackIdsChanged)
 	}
 }
\ No newline at end of file
diff --git a/server/packets/SetSlot.ts b/server/packets/SetSlot.ts
new file mode 100644
index 0000000..1b5168e
--- /dev/null
+++ b/server/packets/SetSlot.ts
@@ -0,0 +1,49 @@
+import { createWriter, IReader, Endian } from "bufferstuff";
+import { IPacket } from "./IPacket";
+import { Packet } from "../enums/Packet";
+
+export class PacketSetSlot implements IPacket {
+	public packetId = Packet.SetSlot;
+	public windowId:number;
+	public slot:number;
+	public itemId:number;
+	public itemCount:number;
+	public itemUses:number;
+
+	public constructor(windowId?:number, slot?:number, itemId?:number, itemCount?:number, itemUses?:number) {
+		if (typeof(windowId) === "number" && typeof(slot) === "number" && typeof(itemId) === "number" && typeof(itemCount) === "number" && typeof(itemUses) === "number") {
+			this.windowId = windowId;
+			this.slot = slot;
+			this.itemId = itemId;
+			this.itemCount = itemCount;
+			this.itemUses = itemUses;
+		} else {
+			this.windowId = Number.MIN_VALUE;
+			this.slot = Number.MIN_VALUE;
+			this.itemId = Number.MIN_VALUE;
+			this.itemCount = Number.MIN_VALUE;
+			this.itemUses = Number.MIN_VALUE;
+		}
+	}
+
+	public readData(reader:IReader) {
+		this.windowId = reader.readByte();
+		this.slot = reader.readShort();
+		this.itemId = reader.readShort();
+		if (this.itemId !== -1) {
+			this.itemCount = reader.readByte();
+			this.itemUses = reader.readShort();
+		}
+
+		return this;
+	}
+
+	public writeData() {
+		const writer = createWriter(Endian.BE, this.itemId === -1 ? 6 : 9).writeUByte(this.packetId).writeByte(this.windowId).writeShort(this.slot).writeShort(this.itemId);
+		if (this.itemId !== -1) {
+			writer.writeByte(this.itemCount);
+			writer.writeShort(this.itemUses);
+		}
+		return writer.toBuffer();
+	}
+}
\ No newline at end of file