diff --git a/src/Inventory.ts b/src/Inventory.ts
index 0091954..0043cdc 100644
--- a/src/Inventory.ts
+++ b/src/Inventory.ts
@@ -6,17 +6,13 @@ export default class Inventory implements HasData {
 
 	readonly size: number
 	readonly columns: number
-	private slots: ItemStack[]
+	private slots: (ItemStack | undefined)[]
 
 	constructor(size: number, columns: number = 9, data: InventoryData = []) {
 		this.size = size
 		this.columns = columns
 		this.slots = []
 
-		// fill with air (default)
-		for (let i = 0; i < this.size; i++) this.slots[i] = new ItemStack(new Item("tiny:air"), 1)
-
-
 		// fill slots with data
 		data.forEach(stack => {
 			this.slots[stack.slot] = new ItemStack(stack.item.id, stack.amount)
@@ -28,21 +24,21 @@ export default class Inventory implements HasData {
 		 else throw new Error(`IndexOutOfBounds: Inventory slot ${index} (0..${this.size})`)
 	}
 
-	get(index: number) {
-		if (index >= 0 && index < this.size) return this.slots[index]
+	get(index: number): ItemStack {
+		if (index >= 0 && index < this.size) return this.slots[index] ?? new ItemStack("tiny:air")
 
 		throw new Error(`IndexOutOfBounds: Inventory slot ${index} (0..${this.size})`)
 	}
 
 	each(cb: (value: ItemStack, index: number) => void) {
-		return this.slots.forEach(cb)
+		return this.slots.forEach((stack, index) => cb(stack || new ItemStack("tiny:air"), index))
 	}
 
 	addItems(stack: ItemStack): ItemStack | null {
 		let { amount } = stack
 
-		for (const i in this.slots) {
-			const slot = this.slots[i]
+		for (const i of this.slots.keys()) {
+			const slot = this.get(i)
 
 			if (amount <= 0) break
 
@@ -67,22 +63,23 @@ export default class Inventory implements HasData {
 	}
 
 	find(item: Item): number {
-		for (const i in this.slots) if (this.slots[i].match(item)) return Number(i)
+		for (const i of this.slots.keys()) if (this.get(i).match(item)) return Number(i)
 
 		return -1
 	}
 
 	emptySlots(): number {
 		let count = 0
-		for (const slot of this.slots) {
-			if (slot.item.id.matches("tiny:air")) count++
-		}
+
+		this.each(stack => {
+			if (stack.item.id.matches("tiny:air")) count++
+		})
 
 		return count
 	}
 
 	firstEmptySlot(): number {
-		for (const i in this.slots) if (this.slots[i].item.id.matches("tiny:air")) return Number(i)
+		for (const i of this.slots.keys()) if (this.get(i).item.id.matches("tiny:air")) return Number(i)
 
 		return -1
 	}
@@ -90,7 +87,7 @@ export default class Inventory implements HasData {
 	getData() {
 		const arr: (ReturnType<ItemStack["getData"]> & {slot: number})[] = []
 
-		this.slots.forEach((slot, index) => {
+		this.each((slot, index) => {
 			if (slot.item.id.matches("tiny:air")) return
 
 			arr.push({ ...slot.getData(), slot: index })