diff --git a/src/services/inventoryService.ts b/src/services/inventoryService.ts
index 5370c74c6..a2071b2c0 100644
--- a/src/services/inventoryService.ts
+++ b/src/services/inventoryService.ts
@@ -668,9 +668,8 @@ export const updateSlots = (
     extraAmount: number
 ): void => {
     inventory[slotName].Slots += slotAmount;
-    if (inventory[slotName].Extra === undefined) {
-        inventory[slotName].Extra = extraAmount;
-    } else {
+    if (extraAmount != 0) {
+        inventory[slotName].Extra ??= 0;
         inventory[slotName].Extra += extraAmount;
     }
 };
diff --git a/src/types/inventoryTypes/inventoryTypes.ts b/src/types/inventoryTypes/inventoryTypes.ts
index e9acbfc82..ed6da027a 100644
--- a/src/types/inventoryTypes/inventoryTypes.ts
+++ b/src/types/inventoryTypes/inventoryTypes.ts
@@ -435,7 +435,7 @@ export enum InventorySlot {
 }
 
 export interface ISlots {
-    Extra: number; // can be undefined, but not if used via mongoose
+    Extra?: number;
     Slots: number;
 }