diff --git a/interfaces/IInventory.js b/interfaces/IInventory.js
index 9e05d99..a8e435f 100644
--- a/interfaces/IInventory.js
+++ b/interfaces/IInventory.js
@@ -84,7 +84,7 @@ OPSkinsAPI.prototype.withdrawInventoryItems = function(items, delivery, callback
 		items = [items];
 	}
 
-	this.post("IInventory", "Withdraw", 1, {"items": items.join(','), "delivery_id64": delivery.id64, "delivery_token": delivery.token, "delivery_message": delivery.message}, function(err, res) {
+	this.post("IInventory", "Withdraw", 1, {"items": items.join(','), "delivery_id64": delivery ? delivery.id64 : undefined, "delivery_token": delivery ? delivery.token : undefined, "delivery_message": delivery ? delivery.message : undefined}, function(err, res) {
 		if (err && !res) {
 			callback(err);
 		} else {