diff --git a/src/js/game/items/boolean_item.js b/src/js/game/items/boolean_item.js
index 38422398..2ff7b0e2 100644
--- a/src/js/game/items/boolean_item.js
+++ b/src/js/game/items/boolean_item.js
@@ -4,6 +4,8 @@ import { types } from "../../savegame/serialization";
 import { BaseItem } from "../base_item";
 import { globalConfig } from "../../core/config";
 
+/** @typedef {0 | 1} Bit **/
+
 export class BooleanItem extends BaseItem {
     static getId() {
         return "boolean_item";
@@ -27,18 +29,18 @@ export class BooleanItem extends BaseItem {
     }
 
     /**
-     * @param {number} value
+     * @param {Bit} value
      */
     constructor(value) {
         super();
-        this.value = value ? 1 : 0;
+        this.value = value;
     }
 
     /**
-     * @param {BaseItem} other
+     * @param {BooleanItem} other
      */
     equalsImpl(other) {
-        return this.value === /** @type {BooleanItem} */ (other).value;
+        return this.value === other.value;
     }
 
     /**
@@ -48,15 +50,19 @@ export class BooleanItem extends BaseItem {
      * @param {DrawParameters} parameters
      */
     drawItemCenteredImpl(x, y, parameters, diameter = globalConfig.defaultItemDiameter) {
-        let sprite;
-        if (this.value) {
-            sprite = Loader.getSprite("sprites/wires/boolean_true.png");
-        } else {
-            sprite = Loader.getSprite("sprites/wires/boolean_false.png");
-        }
+        const value = Boolean(this.value).toString();
+        const sprite = Loader.getSprite(`sprites/wires/boolean_${value}.png`);
         sprite.drawCachedCentered(parameters, x, y, diameter);
     }
 }
 
 export const BOOL_FALSE_SINGLETON = new BooleanItem(0);
 export const BOOL_TRUE_SINGLETON = new BooleanItem(1);
+
+/**
+ * @param {unknown} item
+ * @returns {item is BooleanItem}
+ **/
+export const isBooleanItem = item => {
+    return item instanceof BooleanItem;
+};
diff --git a/src/js/game/items/color_item.js b/src/js/game/items/color_item.js
index 19d26286..7f5946e0 100644
--- a/src/js/game/items/color_item.js
+++ b/src/js/game/items/color_item.js
@@ -30,10 +30,10 @@ export class ColorItem extends BaseItem {
     }
 
     /**
-     * @param {BaseItem} other
+     * @param {ColorItem} other
      */
     equalsImpl(other) {
-        return this.color === /** @type {ColorItem} */ (other).color;
+        return this.color === other.color;
     }
 
     /**
diff --git a/src/js/game/items/shape_item.js b/src/js/game/items/shape_item.js
index d99a7251..58d59c8b 100644
--- a/src/js/game/items/shape_item.js
+++ b/src/js/game/items/shape_item.js
@@ -28,10 +28,10 @@ export class ShapeItem extends BaseItem {
     }
 
     /**
-     * @param {BaseItem} other
+     * @param {ShapeItem} other
      */
     equalsImpl(other) {
-        return this.definition.getHash() === /** @type {ShapeItem} */ (other).definition.getHash();
+        return this.definition.getHash() === other.definition.getHash();
     }
 
     /**
diff --git a/src/js/game/systems/logic_gate.js b/src/js/game/systems/logic_gate.js
index 9fe41250..5161aa67 100644
--- a/src/js/game/systems/logic_gate.js
+++ b/src/js/game/systems/logic_gate.js
@@ -2,8 +2,7 @@ import { LogicGateComponent, enumLogicGateType } from "../components/logic_gate"
 import { GameSystemWithFilter } from "../game_system_with_filter";
 import { BaseItem } from "../base_item";
 import { enumPinSlotType } from "../components/wired_pins";
-import { BOOL_TRUE_SINGLETON, BOOL_FALSE_SINGLETON, BooleanItem } from "../items/boolean_item";
-import { enumItemProcessorTypes } from "../components/item_processor";
+import { BOOL_TRUE_SINGLETON, BOOL_FALSE_SINGLETON, BooleanItem, isBooleanItem } from "../items/boolean_item";
 
 export class LogicGateSystem extends GameSystemWithFilter {
     constructor(root) {
@@ -19,8 +18,7 @@ export class LogicGateSystem extends GameSystemWithFilter {
     }
 
     update() {
-        for (let i = 0; i < this.allEntities.length; ++i) {
-            const entity = this.allEntities[i];
+        this.allEntities.forEach(entity => {
             const logicComp = entity.components.LogicGate;
             const slotComp = entity.components.WiredPins;
 
@@ -48,133 +46,84 @@ export class LogicGateSystem extends GameSystemWithFilter {
             assert(slotComp.slots[0].type === enumPinSlotType.logicalEjector, "Slot 0 should be ejector");
 
             slotComp.slots[0].value = result;
-        }
+        });
     }
 
     /**
      * @param {Array<BaseItem|null>} parameters
-     * @returns {BaseItem}
+     * @returns {BooleanItem}
      */
     compute_AND(parameters) {
         assert(parameters.length === 2, "bad parameter count for AND");
 
-        const param1 = parameters[0];
-        const param2 = parameters[1];
-        if (!param1 || !param2) {
-            // Not enough params
+        const [param1, param2] = parameters;
+
+        if (!isBooleanItem(param1) || !isBooleanItem(param2)) {
             return BOOL_FALSE_SINGLETON;
         }
 
-        const itemType = param1.getItemType();
-
-        if (itemType !== param2.getItemType()) {
-            // Differing type
-            return BOOL_FALSE_SINGLETON;
-        }
-
-        if (itemType === "boolean") {
-            return /** @type {BooleanItem} */ (param1).value && /** @type {BooleanItem} */ (param2).value
-                ? BOOL_TRUE_SINGLETON
-                : BOOL_FALSE_SINGLETON;
-        }
-
-        return BOOL_FALSE_SINGLETON;
+        return param1.value && param2.value ? BOOL_TRUE_SINGLETON : BOOL_FALSE_SINGLETON;
     }
 
     /**
      * @param {Array<BaseItem|null>} parameters
-     * @returns {BaseItem}
+     * @returns {BooleanItem}
      */
     compute_NOT(parameters) {
-        const item = parameters[0];
+        const [item] = parameters;
+
         if (!item) {
             return BOOL_TRUE_SINGLETON;
         }
 
-        if (item.getItemType() !== "boolean") {
-            // Not a boolean actually
+        if (!isBooleanItem(item)) {
             return BOOL_FALSE_SINGLETON;
         }
 
-        const value = /** @type {BooleanItem} */ (item).value;
-        return value ? BOOL_FALSE_SINGLETON : BOOL_TRUE_SINGLETON;
+        return item.value ? BOOL_FALSE_SINGLETON : BOOL_TRUE_SINGLETON;
     }
 
     /**
      * @param {Array<BaseItem|null>} parameters
-     * @returns {BaseItem}
+     * @returns {BooleanItem}
      */
     compute_XOR(parameters) {
         assert(parameters.length === 2, "bad parameter count for XOR");
 
-        const param1 = parameters[0];
-        const param2 = parameters[1];
-        if (!param1 && !param2) {
-            // Not enough params
+        const [param1, param2] = parameters;
+
+        if (!isBooleanItem(param1) || !isBooleanItem(param2)) {
             return BOOL_FALSE_SINGLETON;
         }
 
-        // Check for the right types
-        if (param1 && param1.getItemType() !== "boolean") {
-            return BOOL_FALSE_SINGLETON;
-        }
-
-        if (param2 && param2.getItemType() !== "boolean") {
-            return BOOL_FALSE_SINGLETON;
-        }
-
-        const valueParam1 = param1 ? /** @type {BooleanItem} */ (param1).value : 0;
-        const valueParam2 = param2 ? /** @type {BooleanItem} */ (param2).value : 0;
-
-        return valueParam1 ^ valueParam2 ? BOOL_TRUE_SINGLETON : BOOL_FALSE_SINGLETON;
+        return param1.value ^ param2.value ? BOOL_TRUE_SINGLETON : BOOL_FALSE_SINGLETON;
     }
 
     /**
      * @param {Array<BaseItem|null>} parameters
-     * @returns {BaseItem}
+     * @returns {BooleanItem}
      */
     compute_OR(parameters) {
         assert(parameters.length === 2, "bad parameter count for OR");
 
-        const param1 = parameters[0];
-        const param2 = parameters[1];
-        if (!param1 && !param2) {
-            // Not enough params
+        const [param1, param2] = parameters;
+
+        if (!isBooleanItem(param1) || !isBooleanItem(param2)) {
             return BOOL_FALSE_SINGLETON;
         }
 
-        const valueParam1 =
-            param1 && param1.getItemType() === "boolean" ? /** @type {BooleanItem} */ (param1).value : 0;
-        const valueParam2 =
-            param2 && param2.getItemType() === "boolean" ? /** @type {BooleanItem} */ (param2).value : 0;
-
-        return valueParam1 || valueParam2 ? BOOL_TRUE_SINGLETON : BOOL_FALSE_SINGLETON;
+        return param1.value || param2.value ? BOOL_TRUE_SINGLETON : BOOL_FALSE_SINGLETON;
     }
 
     /**
      * @param {Array<BaseItem|null>} parameters
-     * @returns {BaseItem}
+     * @returns {BaseItem|null}
      */
     compute_IF(parameters) {
         assert(parameters.length === 2, "bad parameter count for IF");
 
-        const flag = parameters[0];
-        const value = parameters[1];
-        if (!flag || !value) {
-            // Not enough params
-            return null;
-        }
+        const [flag, item] = parameters;
 
-        if (flag.getItemType() !== "boolean") {
-            // Flag is not a boolean
-            return null;
-        }
-
-        // pass through item
-        if (/** @type {BooleanItem} */ (flag).value) {
-            return value;
-        }
-
-        return null;
+        return isBooleanItem(flag) && flag.value ? item : null;
     }
 }