diff --git a/src/module/actor/actor-data.ts b/src/module/actor/actor-data.ts
index c45a0cb2..9f12ef3e 100644
--- a/src/module/actor/actor-data.ts
+++ b/src/module/actor/actor-data.ts
@@ -1,23 +1,31 @@
 import { ModifiableData, ResourceData, UsableResource } from "../common/common-data";
+import { DS4 } from "../config";
 import { DS4ItemData } from "../item/item-data";
 
-export type DS4ActorData = Actor.Data<DS4ActorDataType, DS4ItemData>;
+export type DS4ActorData = DS4CharacterData | DS4CreatureData;
 
-type DS4ActorDataType = DS4ActorDataCharacter | DS4ActorDataCreature;
+type ActorType = keyof typeof DS4.i18n.actorTypes;
 
-interface DS4ActorDataBase {
-    attributes: DS4ActorDataAttributes;
-    traits: DS4ActorDataTraits;
-    combatValues: DS4ActorDataCombatValues;
+interface DS4ActorDataHelper<T, U extends ActorType> extends Actor.Data<T, DS4ItemData> {
+    type: U;
 }
 
-interface DS4ActorDataAttributes {
+type DS4CharacterData = DS4ActorDataHelper<DS4CharacterDataData, "character">;
+type DS4CreatureData = DS4ActorDataHelper<DS4CreatureDataData, "creature">;
+
+interface DS4ActorDataDataBase {
+    attributes: DS4ActorDataDataAttributes;
+    traits: DS4ActorDataDataTraits;
+    combatValues: DS4ActorDataDataCombatValues;
+}
+
+interface DS4ActorDataDataAttributes {
     body: ModifiableData<number>;
     mobility: ModifiableData<number>;
     mind: ModifiableData<number>;
 }
 
-interface DS4ActorDataTraits {
+interface DS4ActorDataDataTraits {
     strength: ModifiableData<number>;
     constitution: ModifiableData<number>;
     agility: ModifiableData<number>;
@@ -26,7 +34,7 @@ interface DS4ActorDataTraits {
     aura: ModifiableData<number>;
 }
 
-interface DS4ActorDataCombatValues {
+interface DS4ActorDataDataCombatValues {
     hitPoints: ResourceData<number>;
     defense: ModifiableData<number>;
     initiative: ModifiableData<number>;
@@ -37,34 +45,32 @@ interface DS4ActorDataCombatValues {
     targetedSpellcasting: ModifiableData<number>;
 }
 
-interface DS4ActorDataCharacter extends DS4ActorDataBase {
-    baseInfo: DS4ActorDataCharacterBaseInfo;
-    progression: DS4ActorDataCharacterProgression;
-    language: DS4ActorDataCharacterLanguage;
-    profile: DS4ActorDataCharacterProfile;
-    currency: DS4ActorDataCharacterCurrency;
+interface DS4CharacterDataData extends DS4ActorDataDataBase {
+    baseInfo: DS4CharacterDataDataBaseInfo;
+    progression: DS4CharacterDataDataProgression;
+    language: DS4CharacterDataDataLanguage;
+    profile: DS4CharacterDataDataProfile;
+    currency: DS4CharacterDataDataCurrency;
 }
-
-interface DS4ActorDataCharacterBaseInfo {
+interface DS4CharacterDataDataBaseInfo {
     race: string;
     class: string;
     heroClass: string;
     culture: string;
 }
-
-interface DS4ActorDataCharacterProgression {
+interface DS4CharacterDataDataProgression {
     level: number;
     experiencePoints: number;
     talentPoints: UsableResource<number>;
     progressPoints: UsableResource<number>;
 }
 
-interface DS4ActorDataCharacterLanguage {
+interface DS4CharacterDataDataLanguage {
     languages: string;
     alphabets: string;
 }
 
-interface DS4ActorDataCharacterProfile {
+interface DS4CharacterDataDataProfile {
     biography: string;
     gender: string;
     birthday: string;
@@ -77,21 +83,21 @@ interface DS4ActorDataCharacterProfile {
     specialCharacteristics: string;
 }
 
-interface DS4ActorDataCharacterCurrency {
+interface DS4CharacterDataDataCurrency {
     gold: number;
     silver: number;
     copper: number;
 }
 
-interface DS4ActorDataCreature extends DS4ActorDataBase {
-    baseInfo: DS4ActorDataCreatureBaseInfo;
+interface DS4CreatureDataData extends DS4ActorDataDataBase {
+    baseInfo: DS4CreatureDataDataBaseInfo;
 }
 
 type CreatureType = "animal" | "construct" | "humanoid" | "magicalEntity" | "plantBeing" | "undead";
 
 type SizeCategory = "tiny" | "small" | "normal" | "large" | "huge" | "colossal";
 
-interface DS4ActorDataCreatureBaseInfo {
+interface DS4CreatureDataDataBaseInfo {
     loot: string;
     foeFactor: number;
     creatureType: CreatureType;
diff --git a/src/module/actor/actor.ts b/src/module/actor/actor.ts
index 6c68e460..47623d47 100644
--- a/src/module/actor/actor.ts
+++ b/src/module/actor/actor.ts
@@ -1,6 +1,6 @@
 import { ModifiableData } from "../common/common-data";
 import { DS4Item } from "../item/item";
-import { DS4Armor, DS4Shield, ItemType } from "../item/item-data";
+import { ItemType } from "../item/item-data";
 import { DS4ActorData } from "./actor-data";
 
 export class DS4Actor extends Actor<DS4ActorData, DS4Item> {
@@ -84,10 +84,13 @@ export class DS4Actor extends Actor<DS4ActorData, DS4Item> {
      */
     private _calculateArmorValueOfEquippedItems(): number {
         return this.items
-            .filter((item) => ["armor", "shield"].includes(item.type))
-            .map((item) => item.data.data as DS4Armor | DS4Shield)
-            .filter((itemData) => itemData.equipped)
-            .map((itemData) => itemData.armorValue)
+            .map((item) => {
+                if (item.data.type === "armor" || item.data.type === "shield") {
+                    return item.data.data.equipped ? item.data.data.armorValue : 0;
+                } else {
+                    return 0;
+                }
+            })
             .reduce((a, b) => a + b, 0);
     }
 
diff --git a/src/module/actor/sheets/actor-sheet.ts b/src/module/actor/sheets/actor-sheet.ts
index 470b8e31..c9adc8fc 100644
--- a/src/module/actor/sheets/actor-sheet.ts
+++ b/src/module/actor/sheets/actor-sheet.ts
@@ -128,7 +128,7 @@ export class DS4ActorSheet extends ActorSheet<unknown, DS4Actor> {
      * @param {JQuery.ChangeEvent<HTMLElement>} ev    The originating change event
      * @private
      */
-    private _onItemChange(ev: JQuery.ChangeEvent<HTMLElement>): void {
+    private _onItemChange(ev: JQuery.ChangeEvent): void {
         ev.preventDefault();
         console.log("Current target:", $(ev.currentTarget).get(0)["name"]);
         const el: HTMLFormElement = $(ev.currentTarget).get(0);
diff --git a/src/module/item/item-data.ts b/src/module/item/item-data.ts
index 53736b79..33a9b67a 100644
--- a/src/module/item/item-data.ts
+++ b/src/module/item/item-data.ts
@@ -3,35 +3,53 @@ import { DS4 } from "../config";
 
 export type ItemType = keyof typeof DS4.i18n.itemTypes;
 
-export type DS4ItemData = Item.Data<DS4ItemDataType>;
+export type DS4ItemData =
+    | DS4WeaponData
+    | DS4ArmorData
+    | DS4ShieldData
+    | DS4SpellData
+    | DS4TrinketData
+    | DS4EquipmentData
+    | DS4TalentData
+    | DS4RacialAbilityData
+    | DS4LanguageData
+    | DS4AlphabetData
+    | DS4SpecialCreatureAbilityData;
 
-type DS4ItemDataType =
-    | DS4Weapon
-    | DS4Armor
-    | DS4Shield
-    | DS4Spell
-    | DS4Trinket
-    | DS4Equipment
-    | DS4Talent
-    | DS4RacialAbility
-    | DS4Language
-    | DS4Alphabet
-    | DS4SpecialCreatureAbility;
+interface DS4ItemDataHelper<T, U extends ItemType> extends Item.Data<T> {
+    type: U;
+}
+
+type DS4WeaponData = DS4ItemDataHelper<DS4WeaponDataData, "weapon">;
+type DS4ArmorData = DS4ItemDataHelper<DS4ArmorDataData, "armor">;
+type DS4ShieldData = DS4ItemDataHelper<DS4ShieldDataData, "shield">;
+type DS4SpellData = DS4ItemDataHelper<DS4SpellDataData, "spell">;
+type DS4TrinketData = DS4ItemDataHelper<DS4TrinketDataData, "trinket">;
+type DS4EquipmentData = DS4ItemDataHelper<DS4EquipmentDataData, "equipment">;
+type DS4TalentData = DS4ItemDataHelper<DS4TalentDataData, "talent">;
+type DS4RacialAbilityData = DS4ItemDataHelper<DS4RacialAbilityDataData, "racialAbility">;
+type DS4LanguageData = DS4ItemDataHelper<DS4LanguageDataData, "language">;
+type DS4AlphabetData = DS4ItemDataHelper<DS4AlphabetDataData, "alphabet">;
+type DS4SpecialCreatureAbilityData = DS4ItemDataHelper<DS4SpecialCreatureAbilityDataData, "specialCreatureAbility">;
 
 // types
 
-interface DS4Weapon extends DS4ItemBase, DS4ItemPhysical, DS4ItemEquipable {
+interface DS4WeaponDataData extends DS4ItemDataDataBase, DS4ItemDataDataPhysical, DS4ItemDataDataEquipable {
     attackType: "melee" | "ranged" | "meleeRanged";
     weaponBonus: number;
     opponentDefense: number;
 }
 
-export interface DS4Armor extends DS4ItemBase, DS4ItemPhysical, DS4ItemEquipable, DS4ItemProtective {
+interface DS4ArmorDataData
+    extends DS4ItemDataDataBase,
+        DS4ItemDataDataPhysical,
+        DS4ItemDataDataEquipable,
+        DS4ItemDataDataProtective {
     armorMaterialType: "cloth" | "leather" | "chain" | "plate";
     armorType: "body" | "helmet" | "vambrace" | "greaves" | "vambraceGreaves";
 }
 
-export interface DS4Talent extends DS4ItemBase {
+interface DS4TalentDataData extends DS4ItemDataDataBase {
     rank: DS4TalentRank;
 }
 
@@ -39,7 +57,7 @@ interface DS4TalentRank extends ModifiableData<number> {
     max: number;
 }
 
-interface DS4Spell extends DS4ItemBase, DS4ItemEquipable {
+interface DS4SpellDataData extends DS4ItemDataDataBase, DS4ItemDataDataEquipable {
     spellType: "spellcasting" | "targetedSpellcasting";
     bonus: string;
     spellCategory:
@@ -59,37 +77,41 @@ interface DS4Spell extends DS4ItemBase, DS4ItemEquipable {
     scrollPrice: number;
 }
 
-export interface DS4Shield extends DS4ItemBase, DS4ItemPhysical, DS4ItemEquipable, DS4ItemProtective {}
-interface DS4Trinket extends DS4ItemBase, DS4ItemPhysical, DS4ItemEquipable {}
-interface DS4Equipment extends DS4ItemBase, DS4ItemPhysical {}
-type DS4RacialAbility = DS4ItemBase;
-type DS4Language = DS4ItemBase;
-type DS4Alphabet = DS4ItemBase;
-interface DS4SpecialCreatureAbility extends DS4ItemBase {
+interface DS4ShieldDataData
+    extends DS4ItemDataDataBase,
+        DS4ItemDataDataPhysical,
+        DS4ItemDataDataEquipable,
+        DS4ItemDataDataProtective {}
+interface DS4TrinketDataData extends DS4ItemDataDataBase, DS4ItemDataDataPhysical, DS4ItemDataDataEquipable {}
+interface DS4EquipmentDataData extends DS4ItemDataDataBase, DS4ItemDataDataPhysical {}
+type DS4RacialAbilityDataData = DS4ItemDataDataBase;
+type DS4LanguageDataData = DS4ItemDataDataBase;
+type DS4AlphabetDataData = DS4ItemDataDataBase;
+interface DS4SpecialCreatureAbilityDataData extends DS4ItemDataDataBase {
     experiencePoints: number;
 }
 
 // templates
 
-interface DS4ItemBase {
+interface DS4ItemDataDataBase {
     description: string;
 }
-interface DS4ItemPhysical {
+interface DS4ItemDataDataPhysical {
     quantity: number;
     price: number;
     availability: "hamlet" | "village" | "city" | "elves" | "dwarves" | "nowhere" | "unset";
     storageLocation: string;
 }
 
-export function isDS4ItemDataTypePhysical(input: DS4ItemDataType): boolean {
+export function isDS4ItemDataTypePhysical(input: DS4ItemData["data"]): boolean {
     return "quantity" in input && "price" in input && "availability" in input && "storageLocation" in input;
 }
 
-interface DS4ItemEquipable {
+interface DS4ItemDataDataEquipable {
     equipped: boolean;
 }
 
-interface DS4ItemProtective {
+interface DS4ItemDataDataProtective {
     armorValue: number;
 }
 
diff --git a/src/module/item/item.ts b/src/module/item/item.ts
index 4944a12c..0226b5bb 100644
--- a/src/module/item/item.ts
+++ b/src/module/item/item.ts
@@ -1,4 +1,4 @@
-import { DS4ItemData, DS4Talent } from "./item-data";
+import { DS4ItemData } from "./item-data";
 
 /**
  * Extend the basic Item with some very simple modifications.
@@ -19,8 +19,8 @@ export class DS4Item extends Item<DS4ItemData> {
     }
 
     prepareDerivedData(): void {
-        if (this.type === "talent") {
-            const data = this.data.data as DS4Talent;
+        if (this.data.type === "talent") {
+            const data = this.data.data;
             data.rank.total = data.rank.base + data.rank.mod;
         }
     }