diff --git a/src/data/mystery-encounters/encounters/fiery-fallout-encounter.ts b/src/data/mystery-encounters/encounters/fiery-fallout-encounter.ts
index 8ad013be6fe..69a24469e20 100644
--- a/src/data/mystery-encounters/encounters/fiery-fallout-encounter.ts
+++ b/src/data/mystery-encounters/encounters/fiery-fallout-encounter.ts
@@ -299,7 +299,7 @@ export const FieryFalloutEncounter: MysteryEncounter = MysteryEncounterBuilder.w
 
 function giveLeadPokemonAttackTypeBoostItem() {
   // Give first party pokemon attack type boost item for free at end of battle
-  const leadPokemon = globalScene.getPlayerParty()?.[0];
+  const leadPokemon = globalScene.getPlayerParty()[0];
   if (leadPokemon) {
     // Generate type booster held item, default to Charcoal if item fails to generate
     let item = getNewHeldItemFromCategory(HeldItemCategoryId.TYPE_ATTACK_BOOSTER, leadPokemon);
diff --git a/src/enums/held-item-id.ts b/src/enums/held-item-id.ts
index 0792ffce8b5..d8fc58e28eb 100644
--- a/src/enums/held-item-id.ts
+++ b/src/enums/held-item-id.ts
@@ -129,7 +129,7 @@ export function getHeldItemCategory(itemId: HeldItemId): HeldItemCategoryId {
 }
 
 export function isCategoryId(id: number): boolean {
-  return (id & ITEM_CATEGORY_MASK) === id && id in HeldItemCategoryId;
+  return (Object.values(HeldItemCategoryId) as number[]).includes(id);
 }
 
 export function isItemInCategory(itemId: HeldItemId, category: HeldItemCategoryId): boolean {
diff --git a/src/field/pokemon-held-item-manager.ts b/src/field/pokemon-held-item-manager.ts
index d5a6134c01a..d5bbeea4389 100644
--- a/src/field/pokemon-held-item-manager.ts
+++ b/src/field/pokemon-held-item-manager.ts
@@ -1,9 +1,9 @@
 import { allHeldItems } from "#app/data/data-lists";
 import {
+  type HeldItemCategoryId,
   isCategoryId,
   isItemInCategory,
   isItemInRequested,
-  type HeldItemCategoryId,
   type HeldItemId,
 } from "#app/enums/held-item-id";
 import type { FormChangeItem } from "#enums/form-change-item";
diff --git a/test/mystery-encounter/encounters/fiery-fallout-encounter.test.ts b/test/mystery-encounter/encounters/fiery-fallout-encounter.test.ts
index b5e54a23157..54153246327 100644
--- a/test/mystery-encounter/encounters/fiery-fallout-encounter.test.ts
+++ b/test/mystery-encounter/encounters/fiery-fallout-encounter.test.ts
@@ -180,8 +180,8 @@ describe("Fiery Fallout - Mystery Encounter", () => {
       expect(scene.phaseManager.getCurrentPhase()?.constructor.name).toBe(SelectModifierPhase.name);
 
       const hasAttackBooster = scene
-        .getPlayerParty()?.[0]
-        .heldItemManager.hasItemCategory(HeldItemCategoryId.TYPE_ATTACK_BOOSTER);
+        .getPlayerParty()[0]
+        .heldItemManager.hasItem(HeldItemCategoryId.TYPE_ATTACK_BOOSTER);
       expect(hasAttackBooster).toBe(true);
     });
   });
@@ -266,8 +266,8 @@ describe("Fiery Fallout - Mystery Encounter", () => {
       expect(scene.phaseManager.getCurrentPhase()?.constructor.name).toBe(SelectModifierPhase.name);
 
       const hasAttackBooster = scene
-        .getPlayerParty()?.[0]
-        .heldItemManager.hasItemCategory(HeldItemCategoryId.TYPE_ATTACK_BOOSTER);
+        .getPlayerParty()[0]
+        .heldItemManager.hasItem(HeldItemCategoryId.TYPE_ATTACK_BOOSTER);
       expect(hasAttackBooster).toBe(true);
     });