diff --git a/src/services/inventoryService.ts b/src/services/inventoryService.ts
index 0c5a4cc1..b8e01e53 100644
--- a/src/services/inventoryService.ts
+++ b/src/services/inventoryService.ts
@@ -416,7 +416,7 @@ export const addItem = async (
             const key = { ItemType: typeName, ItemCount: quantity };
 
             const index = inventory.LevelKeys.findIndex(levelKey => levelKey.ItemType == typeName);
-            if (index) {
+            if (index != -1) {
                 inventory.LevelKeys[index].ItemCount += quantity;
             } else {
                 inventory.LevelKeys.push(key);