diff --git a/src/device/attribute/boolDeviceAttribute.ts b/src/device/attribute/boolDeviceAttribute.ts
index aa898ec7..5cf99e4f 100644
--- a/src/device/attribute/boolDeviceAttribute.ts
+++ b/src/device/attribute/boolDeviceAttribute.ts
@@ -1,11 +1,9 @@
-import type { DeviceAttributeModifier, NotJustUndefined, NotUndefined } from './deviceAttribute.js';
+import type { DeviceAttributeModifier } from './deviceAttribute.js';
 import DeviceAttribute from './deviceAttribute.js';
 
-type BoolDeviceAttributeValue = NotJustUndefined<boolean | undefined>;
+export type InitializedBoolDeviceAttribute = BoolDeviceAttribute<true>;
 
-export type InitializedBoolDeviceAttribute = BoolDeviceAttribute<boolean>;
-
-export default class BoolDeviceAttribute<T extends BoolDeviceAttributeValue = BoolDeviceAttributeValue> extends DeviceAttribute<T>
+export default class BoolDeviceAttribute<IsInitialized extends boolean = false> extends DeviceAttribute<boolean, IsInitialized>
 {
     public static createInitialized(
         name: string,
@@ -13,7 +11,7 @@ export default class BoolDeviceAttribute<T extends BoolDeviceAttributeValue = Bo
         modifier: DeviceAttributeModifier,
         initialValue: boolean,
     ): InitializedBoolDeviceAttribute {
-        return new BoolDeviceAttribute<boolean>(name, label, modifier, initialValue);
+        return new BoolDeviceAttribute<true>(name, label, modifier, initialValue);
     }
 
     public static create(
@@ -24,13 +22,11 @@ export default class BoolDeviceAttribute<T extends BoolDeviceAttributeValue = Bo
         return new BoolDeviceAttribute(name, label, modifier, undefined);
     }
 
-    public override fromString(value: string): T {
-        // TODO https://github.com/SlvCtrlPlus/slvctrlplus-server/issues/107
-        // eslint-disable-next-line @typescript-eslint/consistent-type-assertions, @typescript-eslint/no-unsafe-type-assertion
-        return (value === '1') as T;
+    public override fromString(value: string): boolean {
+        return value === '1';
     }
 
-    public override isValidValue(value: unknown): value is NotUndefined<T> {
+    public override isValidValue(value: unknown): value is boolean {
         return typeof value === 'boolean';
     }
 
diff --git a/src/device/attribute/deviceAttribute.ts b/src/device/attribute/deviceAttribute.ts
index 2ad13762..322089f8 100644
--- a/src/device/attribute/deviceAttribute.ts
+++ b/src/device/attribute/deviceAttribute.ts
@@ -1,9 +1,9 @@
 import { Exclude, Expose } from 'class-transformer';
 import type { Float, Int } from '../../util/numbers.js';
 
-export type NotJustUndefined<V> = [V] extends [undefined] ? never : V;
-export type NotUndefined<V> = V extends undefined ? never : V;
-export type AttributeValue = NotJustUndefined<string | Int | Float | boolean | null | undefined>;
+export type AllowedAttributeType = string | Int | Float | boolean | null;
+
+export type AttributeValue<V extends AllowedAttributeType = AllowedAttributeType, IsInitialized extends boolean = false> = IsInitialized extends true ? V : V | undefined;
 
 export enum DeviceAttributeModifier
 {
@@ -12,13 +12,16 @@ export enum DeviceAttributeModifier
     writeOnly = 'wo',
 }
 
-export const isValidAttributeValue = <T extends AttributeValue>(
-    attribute: DeviceAttribute<T> | undefined,
+export const isValidAttributeValue = <V extends AllowedAttributeType, IsInitialized extends boolean = boolean>(
+    attribute: DeviceAttribute<V, IsInitialized> | undefined,
     value: unknown,
-): value is NotUndefined<T> => attribute?.isValidValue(value) ?? false;
+): value is V => attribute?.isValidValue(value) ?? false;
 
 @Exclude()
-export default abstract class DeviceAttribute<T extends AttributeValue = AttributeValue>
+export default abstract class DeviceAttribute<
+    V extends AllowedAttributeType = AllowedAttributeType,
+    IsInitialized extends boolean = false,
+>
 {
     @Expose({ name: 'name' })
     private readonly _name: string;
@@ -30,9 +33,9 @@ export default abstract class DeviceAttribute<T extends AttributeValue = Attribu
     private readonly _modifier: DeviceAttributeModifier;
 
     @Expose({ name: 'value' })
-    private _value: T;
+    private _value: AttributeValue<V, IsInitialized>;
 
-    public constructor(name: string, label: string | undefined, modifier: DeviceAttributeModifier, initialValue: T) {
+    public constructor(name: string, label: string | undefined, modifier: DeviceAttributeModifier, initialValue: AttributeValue<V, IsInitialized>) {
         this._name = name;
         this._label = label;
         this._modifier = modifier;
@@ -58,15 +61,15 @@ export default abstract class DeviceAttribute<T extends AttributeValue = Attribu
     /**
      * @returns the current value or undefined if it has never been set or read from the device
      */
-    public get value(): T {
+    public get value(): AttributeValue<V, IsInitialized> {
         return this._value;
     }
 
-    public set value(value: T) {
+    public set value(value: AttributeValue<V, IsInitialized>) {
         this._value = value;
     }
 
-    public hasValue(): this is { value: T } {
+    public hasValue(): this is { value: V } {
         return this._value !== undefined;
     }
 
@@ -76,7 +79,7 @@ export default abstract class DeviceAttribute<T extends AttributeValue = Attribu
         throw new Error(`Not implemented`);
     }
 
-    public abstract fromString(value: string): T;
+    public abstract fromString(value: string): V;
 
-    public abstract isValidValue(value: unknown): value is NotUndefined<T>;
+    public abstract isValidValue(value: unknown): value is V;
 }
diff --git a/src/device/attribute/floatDeviceAttribute.ts b/src/device/attribute/floatDeviceAttribute.ts
index 619504c9..d7604fe6 100644
--- a/src/device/attribute/floatDeviceAttribute.ts
+++ b/src/device/attribute/floatDeviceAttribute.ts
@@ -1,19 +1,17 @@
-import type { DeviceAttributeModifier, NotJustUndefined } from './deviceAttribute.js';
+import type { AttributeValue, DeviceAttributeModifier } from './deviceAttribute.js';
 import { Float } from '../../util/numbers.js';
 import NumberDeviceAttribute from './numberDeviceAttribute.js';
 
-type FloatDeviceAttributeValue = NotJustUndefined<Float | undefined>;
+export type InitializedFloatGenericDeviceAttribute = FloatDeviceAttribute<true>;
 
-export type InitializedFloatGenericDeviceAttribute = FloatDeviceAttribute<Float>;
-
-export default class FloatDeviceAttribute<T extends FloatDeviceAttributeValue = FloatDeviceAttributeValue> extends NumberDeviceAttribute<T>
+export default class FloatDeviceAttribute<IsInitialized extends boolean = false> extends NumberDeviceAttribute<Float, IsInitialized>
 {
     public constructor(
         name: string,
         label: string | undefined,
         modifier: DeviceAttributeModifier,
         uom: string | undefined,
-        initialValue: T,
+        initialValue: AttributeValue<Float, IsInitialized>,
     ) {
         super(name, label, modifier, uom, initialValue);
     }
@@ -25,7 +23,7 @@ export default class FloatDeviceAttribute<T extends FloatDeviceAttributeValue =
         uom: string | undefined,
         initialValue: Float,
     ): InitializedFloatGenericDeviceAttribute {
-        return new FloatDeviceAttribute<Float>(name, label, modifier, uom, initialValue);
+        return new FloatDeviceAttribute<true>(name, label, modifier, uom, initialValue);
     }
 
     public static create(
@@ -37,16 +35,18 @@ export default class FloatDeviceAttribute<T extends FloatDeviceAttributeValue =
         return new FloatDeviceAttribute(name, label, modifier, uom, undefined);
     }
 
-    public fromString(value: string): T {
+    public fromString(value: string): Float {
         const num = parseFloat(value);
 
         if (isNaN(num)) {
             throw new Error(`Could not convert '${value}' to a valid value for ${this.constructor.name}`);
         }
 
-        // TODO https://github.com/SlvCtrlPlus/slvctrlplus-server/issues/107
-        // eslint-disable-next-line @typescript-eslint/consistent-type-assertions, @typescript-eslint/no-unsafe-type-assertion
-        return Float.from(num) as T;
+        return Float.from(num);
+    }
+
+    public override isValidValue(value: unknown): value is Float {
+        return typeof value === 'number' && Number.isFinite(value);
     }
 
     public override getType(): string {
diff --git a/src/device/attribute/intDeviceAttribute.ts b/src/device/attribute/intDeviceAttribute.ts
index fbdf6d50..84f35f38 100644
--- a/src/device/attribute/intDeviceAttribute.ts
+++ b/src/device/attribute/intDeviceAttribute.ts
@@ -1,11 +1,10 @@
-import type { DeviceAttributeModifier, NotJustUndefined } from './deviceAttribute.js';
+import type { DeviceAttributeModifier } from './deviceAttribute.js';
 import { Int } from '../../util/numbers.js';
 import NumberDeviceAttribute from './numberDeviceAttribute.js';
 
-export type IntAttributeValue = NotJustUndefined<Int | undefined>;
-export type InitializedIntGenericDeviceAttribute = IntDeviceAttribute<Int>;
+export type InitializedIntGenericDeviceAttribute = IntDeviceAttribute<true>;
 
-export default class IntDeviceAttribute<T extends IntAttributeValue = IntAttributeValue> extends NumberDeviceAttribute<T>
+export default class IntDeviceAttribute<IsInitialized extends boolean = false> extends NumberDeviceAttribute<Int, IsInitialized>
 {
     public static createInitialized(
         name: string,
@@ -14,7 +13,7 @@ export default class IntDeviceAttribute<T extends IntAttributeValue = IntAttribu
         uom: string | undefined,
         initialValue: Int,
     ): InitializedIntGenericDeviceAttribute {
-        return new IntDeviceAttribute<Int>(name, label, modifier, uom, initialValue);
+        return new IntDeviceAttribute<true>(name, label, modifier, uom, initialValue);
     }
 
     public static create(
@@ -26,16 +25,18 @@ export default class IntDeviceAttribute<T extends IntAttributeValue = IntAttribu
         return new IntDeviceAttribute(name, label, modifier, uom, undefined);
     }
 
-    public fromString(value: string): T {
+    public fromString(value: string): Int {
         const num = parseInt(value, 10);
 
         if (isNaN(num)) {
             throw new Error(`Could not convert '${value}' to a valid value for ${this.constructor.name}`);
         }
 
-        // TODO https://github.com/SlvCtrlPlus/slvctrlplus-server/issues/107
-        // eslint-disable-next-line @typescript-eslint/consistent-type-assertions, @typescript-eslint/no-unsafe-type-assertion
-        return Int.from(num) as T;
+        return Int.from(num);
+    }
+
+    public override isValidValue(value: unknown): value is Int {
+        return typeof value === 'number' && Number.isInteger(value);
     }
 
     public override getType(): string {
diff --git a/src/device/attribute/intRangeDeviceAttribute.ts b/src/device/attribute/intRangeDeviceAttribute.ts
index 20dc2323..8a408847 100644
--- a/src/device/attribute/intRangeDeviceAttribute.ts
+++ b/src/device/attribute/intRangeDeviceAttribute.ts
@@ -1,12 +1,11 @@
 import { Expose } from 'class-transformer';
-import type { IntAttributeValue } from './intDeviceAttribute.js';
 import { Int } from '../../util/numbers.js';
-import type { DeviceAttributeModifier } from './deviceAttribute.js';
+import type { AttributeValue, DeviceAttributeModifier } from './deviceAttribute.js';
 import NumberDeviceAttribute from './numberDeviceAttribute.js';
 
-export type InitializedIntRangeDeviceAttribute = IntRangeDeviceAttribute<Int>;
+export type InitializedIntRangeDeviceAttribute = IntRangeDeviceAttribute<true>;
 
-export default class IntRangeDeviceAttribute<T extends IntAttributeValue = IntAttributeValue> extends NumberDeviceAttribute<T>
+export default class IntRangeDeviceAttribute<IsInitialized extends boolean = false> extends NumberDeviceAttribute<Int, IsInitialized>
 {
     @Expose({ name: 'min' })
     private _min: Int;
@@ -17,7 +16,16 @@ export default class IntRangeDeviceAttribute<T extends IntAttributeValue = IntAt
     @Expose({ name: 'incrementStep' })
     private readonly _incrementStep: Int = Int.from(1);
 
-    public constructor(name: string, label: string | undefined, modifier: DeviceAttributeModifier, uom: string | undefined, min: Int, max: Int, incrementStep: Int, initialValue: T) {
+    public constructor(
+        name: string,
+        label: string | undefined,
+        modifier: DeviceAttributeModifier,
+        uom: string | undefined,
+        min: Int,
+        max: Int,
+        incrementStep: Int,
+        initialValue: AttributeValue<Int, IsInitialized>,
+    ) {
         super(name, label, modifier, uom, initialValue);
         this._min = min;
         this._max = max;
@@ -34,7 +42,7 @@ export default class IntRangeDeviceAttribute<T extends IntAttributeValue = IntAt
         incrementStep: Int,
         initialValue: Int,
     ): InitializedIntRangeDeviceAttribute {
-        return new IntRangeDeviceAttribute<Int>(name, label, modifier, uom, min, max, incrementStep, initialValue);
+        return new IntRangeDeviceAttribute<true>(name, label, modifier, uom, min, max, incrementStep, initialValue);
     }
 
     public static create(
@@ -69,16 +77,18 @@ export default class IntRangeDeviceAttribute<T extends IntAttributeValue = IntAt
         return this._incrementStep;
     }
 
-    public fromString(value: string): T {
+    public fromString(value: string): Int {
         const res = parseInt(value, 10);
 
         if (isNaN(res)) {
             throw new Error(`Could not convert '${value}' to a valid value for ${this.constructor.name}`);
         }
 
-        // TODO https://github.com/SlvCtrlPlus/slvctrlplus-server/issues/107
-        // eslint-disable-next-line @typescript-eslint/consistent-type-assertions, @typescript-eslint/no-unsafe-type-assertion
-        return res as T;
+        return Int.from(res);
+    }
+
+    public override isValidValue(value: unknown): value is Int {
+        return typeof value === 'number' && Number.isInteger(value);
     }
 
     public override getType(): string {
diff --git a/src/device/attribute/listDeviceAttribute.ts b/src/device/attribute/listDeviceAttribute.ts
index 1e0d8019..488a1b5a 100644
--- a/src/device/attribute/listDeviceAttribute.ts
+++ b/src/device/attribute/listDeviceAttribute.ts
@@ -1,5 +1,5 @@
 import { Expose } from 'class-transformer';
-import type { DeviceAttributeModifier, NotUndefined } from './deviceAttribute.js';
+import type { AttributeValue, DeviceAttributeModifier } from './deviceAttribute.js';
 import DeviceAttribute from './deviceAttribute.js';
 import type { Int } from '../../util/numbers.js';
 
@@ -9,15 +9,15 @@ export type ListDeviceAttributeItem = string | Int;
 export type InitializedListDeviceAttribute<
     IKey extends ListDeviceAttributeItem,
     IValue extends ListDeviceAttributeItem,
-> = ListDeviceAttribute<IKey, IValue, IKey>;
+> = ListDeviceAttribute<IKey, IValue, true>;
 
 export type ListDeviceAttributeOptions<IKey, IValue> = ListDeviceAttributeOption<IKey, IValue>[];
 
 export default class ListDeviceAttribute<
     IKey extends ListDeviceAttributeItem,
     IValue extends ListDeviceAttributeItem,
-    V extends IKey | undefined = IKey | undefined,
-> extends DeviceAttribute<V>
+    IsInitialized extends boolean = false,
+> extends DeviceAttribute<IKey, IsInitialized>
 {
     @Expose({ name: 'values' })
     private _values: ListDeviceAttributeOptions<IKey, IValue>;
@@ -27,7 +27,7 @@ export default class ListDeviceAttribute<
         label: string | undefined,
         modifier: DeviceAttributeModifier,
         values: ListDeviceAttributeOptions<IKey, IValue>,
-        initialValue: V,
+        initialValue: AttributeValue<IKey, IsInitialized>,
     ) {
         super(name, label, modifier, initialValue);
 
@@ -41,7 +41,7 @@ export default class ListDeviceAttribute<
         values: ListDeviceAttributeOptions<IKey, IValue>,
         initialValue: IKey,
     ): InitializedListDeviceAttribute<IKey, IValue> {
-        return new ListDeviceAttribute<IKey, IValue, IKey>(
+        return new ListDeviceAttribute<IKey, IValue, true>(
             name, label, modifier, values, initialValue,
         );
     }
@@ -57,18 +57,18 @@ export default class ListDeviceAttribute<
         );
     }
 
-    public fromString(value: string): V {
+    public fromString(value: string): IKey {
         if (this._values.length === 0 || typeof this._values[0]?.key === 'string') {
-            // TODO https://github.com/SlvCtrlPlus/slvctrlplus-server/issues/107
+            // The value kind (IKey) is chosen by the caller per instance, so TypeScript can't
+            // prove `value`/the parsed number is an IKey here - see issue #107 for details.
             // eslint-disable-next-line @typescript-eslint/consistent-type-assertions, @typescript-eslint/no-unsafe-type-assertion
-            return value as V;
+            return value as IKey;
         }
 
         const parsedInt = parseInt(value, 10);
 
-        // TODO https://github.com/SlvCtrlPlus/slvctrlplus-server/issues/107
         // eslint-disable-next-line @typescript-eslint/consistent-type-assertions, @typescript-eslint/no-unsafe-type-assertion
-        return (isNaN(parsedInt) ? value : parsedInt) as V;
+        return (isNaN(parsedInt) ? value : parsedInt) as IKey;
     }
 
     public get values(): ListDeviceAttributeOptions<IKey, IValue> {
@@ -79,7 +79,7 @@ export default class ListDeviceAttribute<
         this._values = value;
     }
 
-    public isValidValue(value: unknown): value is NotUndefined<V> {
+    public isValidValue(value: unknown): value is IKey {
         if (typeof value === 'string' || typeof value === 'number') {
             return -1 !== this._values.findIndex(entry => entry.key === value);
         }
diff --git a/src/device/attribute/numberDeviceAttribute.ts b/src/device/attribute/numberDeviceAttribute.ts
index 8638fad9..bc9c5b80 100644
--- a/src/device/attribute/numberDeviceAttribute.ts
+++ b/src/device/attribute/numberDeviceAttribute.ts
@@ -1,11 +1,14 @@
-import type { DeviceAttributeModifier, NotJustUndefined, NotUndefined } from './deviceAttribute.js';
+import type { AttributeValue, DeviceAttributeModifier } from './deviceAttribute.js';
 import DeviceAttribute from './deviceAttribute.js';
 import { Expose } from 'class-transformer';
 import type { Float, Int } from '../../util/numbers.js';
 
-export type NumberAttributeValue = NotJustUndefined<Int | Float | undefined>;
+export type NumberAttributeValue = Int | Float;
 
-export default abstract class NumberDeviceAttribute<T extends NumberAttributeValue = NumberAttributeValue> extends DeviceAttribute<T>
+export default abstract class NumberDeviceAttribute<
+    V extends NumberAttributeValue = NumberAttributeValue,
+    IsInitialized extends boolean = false,
+> extends DeviceAttribute<V, IsInitialized>
 {
     @Expose({ name: 'uom' })
     private readonly _uom: string | undefined;
@@ -15,7 +18,7 @@ export default abstract class NumberDeviceAttribute<T extends NumberAttributeVal
         label: string | undefined,
         modifier: DeviceAttributeModifier,
         uom: string | undefined,
-        initialValue: T,
+        initialValue: AttributeValue<V, IsInitialized>,
     ) {
         super(name, label, modifier, initialValue);
         this._uom = uom;
@@ -24,8 +27,4 @@ export default abstract class NumberDeviceAttribute<T extends NumberAttributeVal
     public get uom(): string | undefined {
         return this._uom;
     }
-
-    public override isValidValue(value: unknown): value is NotUndefined<T> {
-        return typeof value === 'number';
-    }
 }
diff --git a/src/device/attribute/strDeviceAttribute.ts b/src/device/attribute/strDeviceAttribute.ts
index 33a6e6a6..9c35a942 100644
--- a/src/device/attribute/strDeviceAttribute.ts
+++ b/src/device/attribute/strDeviceAttribute.ts
@@ -1,11 +1,9 @@
-import type { DeviceAttributeModifier, NotJustUndefined, NotUndefined } from './deviceAttribute.js';
+import type { DeviceAttributeModifier } from './deviceAttribute.js';
 import DeviceAttribute from './deviceAttribute.js';
 
-type StrDeviceAttributeValue = NotJustUndefined<string | undefined>;
+export type InitializedStrDeviceAttribute = StrDeviceAttribute<true>;
 
-export type InitializedStrDeviceAttribute = StrDeviceAttribute<string>;
-
-export default class StrDeviceAttribute<T extends StrDeviceAttributeValue = StrDeviceAttributeValue> extends DeviceAttribute<T>
+export default class StrDeviceAttribute<IsInitialized extends boolean = false> extends DeviceAttribute<string, IsInitialized>
 {
     public static createInitialized(
         name: string,
@@ -13,25 +11,23 @@ export default class StrDeviceAttribute<T extends StrDeviceAttributeValue = StrD
         modifier: DeviceAttributeModifier,
         initialValue: string,
     ): InitializedStrDeviceAttribute {
-        return new StrDeviceAttribute<string>(name, label, modifier, initialValue);
+        return new StrDeviceAttribute<true>(name, label, modifier, initialValue);
     }
 
     public static create(
         name: string,
         label: string | undefined,
         modifier: DeviceAttributeModifier,
-        initialValue?: StrDeviceAttributeValue,
+        initialValue?: string,
     ): StrDeviceAttribute {
         return new StrDeviceAttribute(name, label, modifier, initialValue);
     }
 
-    public override fromString(value: string): T {
-        // TODO https://github.com/SlvCtrlPlus/slvctrlplus-server/issues/107
-        // eslint-disable-next-line @typescript-eslint/consistent-type-assertions, @typescript-eslint/no-unsafe-type-assertion
-        return value as T;
+    public override fromString(value: string): string {
+        return value;
     }
 
-    public override isValidValue(value: unknown): value is NotUndefined<T> {
+    public override isValidValue(value: unknown): value is string {
         return typeof value === 'string';
     }
 
diff --git a/src/device/protocol/buttplugIo/buttplugIoDevice.ts b/src/device/protocol/buttplugIo/buttplugIoDevice.ts
index 2590d1d5..881d048e 100644
--- a/src/device/protocol/buttplugIo/buttplugIoDevice.ts
+++ b/src/device/protocol/buttplugIo/buttplugIoDevice.ts
@@ -3,9 +3,12 @@ import type { ButtplugClientDevice, SensorType } from 'buttplug';
 import { ActuatorType } from 'buttplug';
 import type { AttributeKeyOf, AttributeValueOf, DeviceInfo } from '../../device.js';
 import Device from '../../device.js';
+import type { InitializedIntRangeDeviceAttribute } from '../../attribute/intRangeDeviceAttribute.js';
 import IntRangeDeviceAttribute from '../../attribute/intRangeDeviceAttribute.js';
+import type { InitializedBoolDeviceAttribute } from '../../attribute/boolDeviceAttribute.js';
 import BoolDeviceAttribute from '../../attribute/boolDeviceAttribute.js';
 import { Int } from '../../../util/numbers.js';
+import type { InitializedIntGenericDeviceAttribute } from '../../attribute/intDeviceAttribute.js';
 import IntDeviceAttribute from '../../attribute/intDeviceAttribute.js';
 import { DeviceAttributeModifier } from '../../attribute/deviceAttribute.js';
 import type EventEmitter from 'events';
@@ -18,9 +21,11 @@ type ButtplugSensorTypeKey = `${SensorType}-${number}`;
 
 export type ButtplugIoDeviceAttributeKey = ButtplugActuatorTypeKey | ButtplugSensorTypeKey;
 
+// All attributes are always constructed with an initial value (see buttplugIoDeviceFactory.ts),
+// so they use the Initialized* variants to reflect that at the type level.
 export type ButtplugIoDeviceAttributes = Record<
     ButtplugIoDeviceAttributeKey,
-    IntRangeDeviceAttribute | BoolDeviceAttribute | IntDeviceAttribute | undefined
+    InitializedIntRangeDeviceAttribute | InitializedBoolDeviceAttribute | InitializedIntGenericDeviceAttribute | undefined
 >;
 
 type AttributeValue<K extends keyof ButtplugIoDeviceAttributes> = AttributeValueOf<ButtplugIoDeviceAttributes, K>;
@@ -76,6 +81,10 @@ export default class ButtplugIoDevice extends Device<ButtplugIoDeviceAttributes>
             throw new Error(`Attribute with name '${attributeName}' is readonly`);
         }
 
+        // TypeScript now guarantees `value` is defined for a caller bound by the typed setAttribute
+        // signature above, but this is still reachable via the untyped AnyDevice interface (e.g.
+        // automation scripts), so the runtime guard stays.
+        // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
         if (undefined === value) {
             throw new Error(`Value to be set for attribute '${attributeName}' cannot be undefined`);
         }
diff --git a/src/device/protocol/estim2b/estim2bDevice.ts b/src/device/protocol/estim2b/estim2bDevice.ts
index d4b1acf3..93b28f6a 100644
--- a/src/device/protocol/estim2b/estim2bDevice.ts
+++ b/src/device/protocol/estim2b/estim2bDevice.ts
@@ -1,13 +1,14 @@
 import type { AttributeKeyOf, AttributeValueOf, DeviceInfo } from '../../device.js';
+import type { InitializedIntRangeDeviceAttribute } from '../../attribute/intRangeDeviceAttribute.js';
 import IntRangeDeviceAttribute from '../../attribute/intRangeDeviceAttribute.js';
 import type { Estim2bCommand, EStim2bStatus } from './estim2bProtocol.js';
 import type EStim2bProtocol from './estim2bProtocol.js';
 import { EStim2bMode } from './estim2bProtocol.js';
 import { Exclude, Expose } from 'class-transformer';
 import { Int } from '../../../util/numbers.js';
-import type BoolDeviceAttribute from '../../attribute/boolDeviceAttribute.js';
-import type StrDeviceAttribute from '../../attribute/strDeviceAttribute.js';
-import type ListDeviceAttribute from '../../attribute/listDeviceAttribute.js';
+import type { InitializedBoolDeviceAttribute } from '../../attribute/boolDeviceAttribute.js';
+import type { InitializedStrDeviceAttribute } from '../../attribute/strDeviceAttribute.js';
+import type { InitializedListDeviceAttribute } from '../../attribute/listDeviceAttribute.js';
 import { DeviceAttributeModifier, isValidAttributeValue } from '../../attribute/deviceAttribute.js';
 import type DeviceBidirectionalTransport from '../../transport/deviceBidirectionalTransport.js';
 import PeripheralDevice from '../../peripheralDevice.js';
@@ -15,15 +16,18 @@ import { getErrorFromDecodeResult } from '../deviceProtocol.js';
 import type EventEmitter from 'events';
 import type Logger from '../../../logging/Logger.js';
 
+// All attributes below are always constructed with an initial value (see estim2bDeviceFactory.ts
+// and setModeBasedAttributes()/updateAttributeValues() in this file), so they use the Initialized*
+// variants to reflect that at the type level.
 export type EStim2bDeviceAttributes = {
-    mode: ListDeviceAttribute<Int, string>;
-    channelALevel: IntRangeDeviceAttribute;
-    channelBLevel: IntRangeDeviceAttribute;
-    pulseFrequency?: IntRangeDeviceAttribute;
-    pulsePwm?: IntRangeDeviceAttribute;
-    channelsJoined: BoolDeviceAttribute;
-    highPowerMode: BoolDeviceAttribute;
-    batteryStatus: StrDeviceAttribute;
+    mode: InitializedListDeviceAttribute<Int, string>;
+    channelALevel: InitializedIntRangeDeviceAttribute;
+    channelBLevel: InitializedIntRangeDeviceAttribute;
+    pulseFrequency?: InitializedIntRangeDeviceAttribute;
+    pulsePwm?: InitializedIntRangeDeviceAttribute;
+    channelsJoined: InitializedBoolDeviceAttribute;
+    highPowerMode: InitializedBoolDeviceAttribute;
+    batteryStatus: InitializedStrDeviceAttribute;
 };
 
 export type EStim2bBatteryStatus = 'mains' | 'full' | 'medium' | 'low' | 'critical';
@@ -234,7 +238,7 @@ export default class EStim2bDevice extends PeripheralDevice<EStim2bProtocol, ESt
         };
     }
 
-    private static createPulsePwmAttribute(label: string, currentStatus: EStim2bStatus): IntRangeDeviceAttribute {
+    private static createPulsePwmAttribute(label: string, currentStatus: EStim2bStatus): InitializedIntRangeDeviceAttribute {
         return IntRangeDeviceAttribute.createInitialized(
             'pulsePwm',
             label,
@@ -247,7 +251,7 @@ export default class EStim2bDevice extends PeripheralDevice<EStim2bProtocol, ESt
         );
     }
 
-    private static createPulseFrequencyAttribute(label: string, currentStatus: EStim2bStatus): IntRangeDeviceAttribute {
+    private static createPulseFrequencyAttribute(label: string, currentStatus: EStim2bStatus): InitializedIntRangeDeviceAttribute {
         return IntRangeDeviceAttribute.createInitialized(
             'pulseFrequency',
             label,
diff --git a/src/device/protocol/virtual/audio/piperVirtualDeviceLogic.ts b/src/device/protocol/virtual/audio/piperVirtualDeviceLogic.ts
index 4f8fbcfc..7ccfd149 100644
--- a/src/device/protocol/virtual/audio/piperVirtualDeviceLogic.ts
+++ b/src/device/protocol/virtual/audio/piperVirtualDeviceLogic.ts
@@ -5,6 +5,7 @@ import type { Readable, Writable } from 'stream';
 import { DeviceAttributeModifier } from '../../../attribute/deviceAttribute.js';
 import StrDeviceAttribute from '../../../attribute/strDeviceAttribute.js';
 import type VirtualDevice from '../virtualDevice.js';
+import type { InitializedBoolDeviceAttribute } from '../../../attribute/boolDeviceAttribute.js';
 import BoolDeviceAttribute from '../../../attribute/boolDeviceAttribute.js';
 import type Logger from '../../../../logging/Logger.js';
 import { spawnProcess } from '../../../../util/process.js';
@@ -29,7 +30,7 @@ type PiperModelMetadata = Static<typeof PiperModelMetadataSchema>;
 
 type PiperVirtualDeviceAttributes = {
     text: StrDeviceAttribute;
-    queuing: BoolDeviceAttribute;
+    queuing: InitializedBoolDeviceAttribute;
 };
 
 export default class PiperVirtualDeviceLogic extends VirtualDeviceLogic<
diff --git a/src/device/protocol/virtual/audio/ttsVirtualDeviceLogic.ts b/src/device/protocol/virtual/audio/ttsVirtualDeviceLogic.ts
index d565b484..77310199 100644
--- a/src/device/protocol/virtual/audio/ttsVirtualDeviceLogic.ts
+++ b/src/device/protocol/virtual/audio/ttsVirtualDeviceLogic.ts
@@ -3,7 +3,9 @@ import StrDeviceAttribute from '../../../attribute/strDeviceAttribute.js';
 import VirtualDeviceLogic from '../virtualDeviceLogic.js';
 import say from 'say';
 import type VirtualDevice from '../virtualDevice.js';
+import type { InitializedBoolDeviceAttribute } from '../../../attribute/boolDeviceAttribute.js';
 import BoolDeviceAttribute from '../../../attribute/boolDeviceAttribute.js';
+import type { InitializedIntGenericDeviceAttribute } from '../../../attribute/intDeviceAttribute.js';
 import IntDeviceAttribute from '../../../attribute/intDeviceAttribute.js';
 import { Int } from '../../../../util/numbers.js';
 import type Logger from '../../../../logging/Logger.js';
@@ -11,9 +13,9 @@ import type { TtsVirtualDeviceConfig } from './ttsVirtualDeviceConfig.js';
 
 type TtsVirtualDeviceAttributes = {
     text: StrDeviceAttribute;
-    speaking: BoolDeviceAttribute;
-    queuing: BoolDeviceAttribute;
-    queueLength: IntDeviceAttribute;
+    speaking: InitializedBoolDeviceAttribute;
+    queuing: InitializedBoolDeviceAttribute;
+    queueLength: InitializedIntGenericDeviceAttribute;
 };
 
 export default class TtsVirtualDeviceLogic extends VirtualDeviceLogic<
diff --git a/src/device/protocol/zc95/zc95Device.ts b/src/device/protocol/zc95/zc95Device.ts
index bcdf4039..ca94da8a 100644
--- a/src/device/protocol/zc95/zc95Device.ts
+++ b/src/device/protocol/zc95/zc95Device.ts
@@ -48,7 +48,7 @@ export type Zc95DevicePowerChannelAttributes = Record<Zc95DevicePowerChannelAttr
 type Zc95DevicePatternAttributesKeyPrefix = `patternAttribute`;
 type Zc95DevicePatternAttributesKey = `${Zc95DevicePatternAttributesKeyPrefix}${number}`;
 
-type Zc95DevicePatternAttributes = Partial<Record<Zc95DevicePatternAttributesKey, InitializedIntRangeDeviceAttribute | ListDeviceAttribute<Int, string>>>;
+type Zc95DevicePatternAttributes = Partial<Record<Zc95DevicePatternAttributesKey, InitializedIntRangeDeviceAttribute | InitializedListDeviceAttribute<Int, string>>>;
 
 export type Zc95DeviceAttributes = AllOrNone<Zc95DevicePowerChannelAttributes> & Zc95DevicePatternAttributes
     & Required<RequiredZc95DeviceAttributes>;
@@ -161,7 +161,7 @@ export default class Zc95Device extends PeripheralDevice<Zc95Protocol, Zc95Devic
             throw new Error('Cannot set channel power before all channel values have been initialized');
         }
 
-        const tmpData: { [K in keyof Zc95DevicePowerChannelAttributes]-?: InitializedIntRangeDeviceAttribute['value'] } = {
+        const tmpData: { [K in keyof Zc95DevicePowerChannelAttributes]-?: Int } = {
             powerChannel1: this.attributes.powerChannel1.value,
             powerChannel2: this.attributes.powerChannel2.value,
             powerChannel3: this.attributes.powerChannel3.value,
@@ -323,7 +323,11 @@ export default class Zc95Device extends PeripheralDevice<Zc95Protocol, Zc95Devic
     }
 
     private static allPowerChannelValuesDefined(attrs: Partial<Zc95DevicePowerChannelAttributes>): attrs is {
-        [K in keyof Zc95DevicePowerChannelAttributes]-?: InitializedIntRangeDeviceAttribute
+        // Power channel attributes are constructed unset (see getChannelPowerAttribute()) and their
+        // value is assigned later, so we can't use InitializedIntRangeDeviceAttribute here (a
+        // different, incompatible instantiation of IntRangeDeviceAttribute) - intersecting with
+        // `{ value: Int }` instead narrows just the value's definedness.
+        [K in keyof Zc95DevicePowerChannelAttributes]-?: Zc95DevicePowerChannelAttributes[K] & { value: Int }
     } {
         return attrs.powerChannel1?.value !== undefined
             && attrs.powerChannel2?.value !== undefined
diff --git a/tests/type/device/buttplugIo.test-d.ts b/tests/type/device/buttplugIo.test-d.ts
index c0f85845..b99b1cc4 100644
--- a/tests/type/device/buttplugIo.test-d.ts
+++ b/tests/type/device/buttplugIo.test-d.ts
@@ -4,10 +4,11 @@ import { Int } from '../../../src/util/numbers.js';
 
 declare const device: ButtplugIoDevice;
 
-// any valid actuator/sensor attribute key: Int | boolean | undefined
-expectTypeOf(device.setAttribute('Vibrate-0', Int.from(50))).toEqualTypeOf<Promise<Int | boolean | undefined>>();
-expectTypeOf(device.setAttribute('Rotate-1', true)).toEqualTypeOf<Promise<Int | boolean | undefined>>();
-expectTypeOf(device.setAttribute('Battery-0', undefined)).toEqualTypeOf<Promise<Int | boolean | undefined>>();
+// any valid actuator/sensor attribute key: Int | boolean (initialized attribute, always has a value)
+expectTypeOf(device.setAttribute('Vibrate-0', Int.from(50))).toEqualTypeOf<Promise<Int | boolean>>();
+expectTypeOf(device.setAttribute('Rotate-1', true)).toEqualTypeOf<Promise<Int | boolean>>();
+// @ts-expect-error attribute value cannot be undefined
+device.setAttribute('Battery-0', undefined);
 // @ts-expect-error attribute value cannot be a string
 device.setAttribute('Vibrate-0', 'fast');
 
diff --git a/tests/type/device/estim2b.test-d.ts b/tests/type/device/estim2b.test-d.ts
index c96a6ea4..f7d8e62d 100644
--- a/tests/type/device/estim2b.test-d.ts
+++ b/tests/type/device/estim2b.test-d.ts
@@ -4,32 +4,33 @@ import { Int } from '../../../src/util/numbers.js';
 
 declare const device: EStim2bDevice;
 
-// mode: Int (list attribute key) | undefined
-expectTypeOf(device.setAttribute('mode', Int.from(0))).toEqualTypeOf<Promise<Int | undefined>>();
-expectTypeOf(device.setAttribute('mode', undefined)).toEqualTypeOf<Promise<Int | undefined>>();
+// mode: Int (initialized list attribute, always has a value)
+expectTypeOf(device.setAttribute('mode', Int.from(0))).toEqualTypeOf<Promise<Int>>();
+// @ts-expect-error mode is always initialized and does not accept undefined
+device.setAttribute('mode', undefined);
 // @ts-expect-error mode does not accept a string value
 device.setAttribute('mode', 'bounce');
 
-// channelALevel / channelBLevel: Int | undefined
-expectTypeOf(device.setAttribute('channelALevel', Int.from(50))).toEqualTypeOf<Promise<Int | undefined>>();
-expectTypeOf(device.setAttribute('channelBLevel', Int.from(50))).toEqualTypeOf<Promise<Int | undefined>>();
+// channelALevel / channelBLevel: Int (initialized attribute, always has a value)
+expectTypeOf(device.setAttribute('channelALevel', Int.from(50))).toEqualTypeOf<Promise<Int>>();
+expectTypeOf(device.setAttribute('channelBLevel', Int.from(50))).toEqualTypeOf<Promise<Int>>();
 // @ts-expect-error channelALevel does not accept a boolean value
 device.setAttribute('channelALevel', true);
 
-// pulseFrequency / pulsePwm: Int | undefined
-expectTypeOf(device.setAttribute('pulseFrequency', Int.from(10))).toEqualTypeOf<Promise<Int | undefined>>();
-expectTypeOf(device.setAttribute('pulsePwm', Int.from(10))).toEqualTypeOf<Promise<Int | undefined>>();
+// pulseFrequency / pulsePwm: Int (initialized attribute, always has a value)
+expectTypeOf(device.setAttribute('pulseFrequency', Int.from(10))).toEqualTypeOf<Promise<Int>>();
+expectTypeOf(device.setAttribute('pulsePwm', Int.from(10))).toEqualTypeOf<Promise<Int>>();
 // @ts-expect-error pulseFrequency does not accept a string value
 device.setAttribute('pulseFrequency', '10');
 
-// channelsJoined / highPowerMode: boolean | undefined
-expectTypeOf(device.setAttribute('channelsJoined', true)).toEqualTypeOf<Promise<boolean | undefined>>();
-expectTypeOf(device.setAttribute('highPowerMode', false)).toEqualTypeOf<Promise<boolean | undefined>>();
+// channelsJoined / highPowerMode: boolean (initialized attribute, always has a value)
+expectTypeOf(device.setAttribute('channelsJoined', true)).toEqualTypeOf<Promise<boolean>>();
+expectTypeOf(device.setAttribute('highPowerMode', false)).toEqualTypeOf<Promise<boolean>>();
 // @ts-expect-error highPowerMode does not accept an Int value
 device.setAttribute('highPowerMode', Int.from(1));
 
-// batteryStatus: string | undefined
-expectTypeOf(device.setAttribute('batteryStatus', 'mains')).toEqualTypeOf<Promise<string | undefined>>();
+// batteryStatus: string (initialized attribute, always has a value)
+expectTypeOf(device.setAttribute('batteryStatus', 'mains')).toEqualTypeOf<Promise<string>>();
 // @ts-expect-error batteryStatus does not accept a boolean value
 device.setAttribute('batteryStatus', true);
 
diff --git a/tests/type/device/virtual/virtual.test-d.ts b/tests/type/device/virtual/virtual.test-d.ts
index 1514e6f6..e191fafe 100644
--- a/tests/type/device/virtual/virtual.test-d.ts
+++ b/tests/type/device/virtual/virtual.test-d.ts
@@ -11,14 +11,14 @@ expectTypeOf(device.setAttribute('text', undefined)).toEqualTypeOf<Promise<strin
 // @ts-expect-error text does not accept an Int value
 device.setAttribute('text', Int.from(1));
 
-// speaking / queuing: boolean | undefined
-expectTypeOf(device.setAttribute('speaking', true)).toEqualTypeOf<Promise<boolean | undefined>>();
-expectTypeOf(device.setAttribute('queuing', false)).toEqualTypeOf<Promise<boolean | undefined>>();
+// speaking / queuing: boolean (initialized attribute, always has a value)
+expectTypeOf(device.setAttribute('speaking', true)).toEqualTypeOf<Promise<boolean>>();
+expectTypeOf(device.setAttribute('queuing', false)).toEqualTypeOf<Promise<boolean>>();
 // @ts-expect-error queuing does not accept a string value
 device.setAttribute('queuing', 'yes');
 
-// queueLength: Int | undefined
-expectTypeOf(device.setAttribute('queueLength', Int.from(3))).toEqualTypeOf<Promise<Int | undefined>>();
+// queueLength: Int (initialized attribute, always has a value)
+expectTypeOf(device.setAttribute('queueLength', Int.from(3))).toEqualTypeOf<Promise<Int>>();
 // @ts-expect-error queueLength does not accept a boolean value
 device.setAttribute('queueLength', true);
 
diff --git a/tests/type/device/zc95/zc95.test-d.ts b/tests/type/device/zc95/zc95.test-d.ts
index a49e234c..16c64f95 100644
--- a/tests/type/device/zc95/zc95.test-d.ts
+++ b/tests/type/device/zc95/zc95.test-d.ts
@@ -20,8 +20,8 @@ expectTypeOf(device.setAttribute('powerChannel4', Int.from(50))).toEqualTypeOf<P
 // @ts-expect-error powerChannel5 is not a valid power channel index
 device.setAttribute('powerChannel5', Int.from(50));
 
-// patternAttribute<N> (dynamic, numeric suffix): Int | undefined
-expectTypeOf(device.setAttribute('patternAttribute3', Int.from(10))).toEqualTypeOf<Promise<Int | undefined>>();
+// patternAttribute<N> (dynamic, numeric suffix, initialized attribute, always has a value): Int
+expectTypeOf(device.setAttribute('patternAttribute3', Int.from(10))).toEqualTypeOf<Promise<Int>>();
 // @ts-expect-error patternAttribute suffix must be numeric
 device.setAttribute('patternAttributeFoo', Int.from(10));
 
diff --git a/tests/unit/device/attribute/floatDeviceAttribute.spec.ts b/tests/unit/device/attribute/floatDeviceAttribute.spec.ts
new file mode 100644
index 00000000..7d958b94
--- /dev/null
+++ b/tests/unit/device/attribute/floatDeviceAttribute.spec.ts
@@ -0,0 +1,21 @@
+import { describe, it, expect } from 'vitest';
+import FloatDeviceAttribute from '../../../../src/device/attribute/floatDeviceAttribute.js';
+import { DeviceAttributeModifier } from '../../../../src/device/attribute/deviceAttribute.js';
+
+describe('FloatDeviceAttribute', () => {
+
+    const attribute = FloatDeviceAttribute.create('attrName', undefined, DeviceAttributeModifier.readWrite, undefined);
+
+    it.each([
+        { value: 5.5, expected: true },
+        { value: 0, expected: true },
+        { value: -5.5, expected: true },
+        { value: NaN, expected: false },
+        { value: Infinity, expected: false },
+        { value: -Infinity, expected: false },
+        { value: '5.5', expected: false },
+        { value: true, expected: false },
+    ])('returns $expected for isValidValue($value)', ({ value, expected }) => {
+        expect(attribute.isValidValue(value)).toStrictEqual(expected);
+    });
+});
diff --git a/tests/unit/device/attribute/intDeviceAttribute.spec.ts b/tests/unit/device/attribute/intDeviceAttribute.spec.ts
new file mode 100644
index 00000000..7481da4a
--- /dev/null
+++ b/tests/unit/device/attribute/intDeviceAttribute.spec.ts
@@ -0,0 +1,22 @@
+import { describe, it, expect } from 'vitest';
+import IntDeviceAttribute from '../../../../src/device/attribute/intDeviceAttribute.js';
+import { DeviceAttributeModifier } from '../../../../src/device/attribute/deviceAttribute.js';
+
+describe('IntDeviceAttribute', () => {
+
+    const attribute = IntDeviceAttribute.create('attrName', undefined, DeviceAttributeModifier.readWrite, undefined);
+
+    it.each([
+        { value: 5, expected: true },
+        { value: 0, expected: true },
+        { value: -5, expected: true },
+        { value: 1.5, expected: false },
+        { value: NaN, expected: false },
+        { value: Infinity, expected: false },
+        { value: -Infinity, expected: false },
+        { value: '5', expected: false },
+        { value: true, expected: false },
+    ])('returns $expected for isValidValue($value)', ({ value, expected }) => {
+        expect(attribute.isValidValue(value)).toStrictEqual(expected);
+    });
+});
diff --git a/tests/unit/device/attribute/intRangeDeviceAttribute.spec.ts b/tests/unit/device/attribute/intRangeDeviceAttribute.spec.ts
new file mode 100644
index 00000000..44c9e72e
--- /dev/null
+++ b/tests/unit/device/attribute/intRangeDeviceAttribute.spec.ts
@@ -0,0 +1,31 @@
+import { describe, it, expect } from 'vitest';
+import IntRangeDeviceAttribute from '../../../../src/device/attribute/intRangeDeviceAttribute.js';
+import { DeviceAttributeModifier } from '../../../../src/device/attribute/deviceAttribute.js';
+import { Int } from '../../../../src/util/numbers.js';
+
+describe('IntRangeDeviceAttribute', () => {
+
+    const attribute = IntRangeDeviceAttribute.create(
+        'attrName',
+        undefined,
+        DeviceAttributeModifier.readWrite,
+        undefined,
+        Int.ZERO,
+        Int.from(100),
+        Int.from(1),
+    );
+
+    it.each([
+        { value: 5, expected: true },
+        { value: 0, expected: true },
+        { value: -5, expected: true },
+        { value: 1.5, expected: false },
+        { value: NaN, expected: false },
+        { value: Infinity, expected: false },
+        { value: -Infinity, expected: false },
+        { value: '5', expected: false },
+        { value: true, expected: false },
+    ])('returns $expected for isValidValue($value)', ({ value, expected }) => {
+        expect(attribute.isValidValue(value)).toStrictEqual(expected);
+    });
+});
diff --git a/tests/unit/device/protocol/buttplugIo/buttplugIoDevice.spec.ts b/tests/unit/device/protocol/buttplugIo/buttplugIoDevice.spec.ts
index 2ff31172..53a4c1a5 100644
--- a/tests/unit/device/protocol/buttplugIo/buttplugIoDevice.spec.ts
+++ b/tests/unit/device/protocol/buttplugIo/buttplugIoDevice.spec.ts
@@ -7,6 +7,7 @@ import ButtplugIoDevice, {
     ButtplugIoDeviceAttributes
 } from "../../../../../src/device/protocol/buttplugIo/buttplugIoDevice.js";
 import {DeviceAttributeModifier} from "../../../../../src/device/attribute/deviceAttribute.js";
+import type {AnyDevice} from "../../../../../src/device/device.js";
 import {Int} from "../../../../../src/util/numbers.js";
 import {describe, it, expect} from "vitest";
 import {mock} from "vitest-mock-extended";
@@ -52,7 +53,7 @@ describe('ButtplugIoDevice', () => {
         const buttplugDeviceMock = mock<ButtplugClientDevice>();
         const boolAttrKey: ButtplugIoDeviceAttributeKey = 'Rotate-1';
 
-        const boolAttr = BoolDeviceAttribute.create(boolAttrKey, undefined, DeviceAttributeModifier.readWrite);
+        const boolAttr = BoolDeviceAttribute.createInitialized(boolAttrKey, undefined, DeviceAttributeModifier.readWrite, true);
 
         const device = createDevice(
             buttplugDeviceMock,
@@ -75,7 +76,7 @@ describe('ButtplugIoDevice', () => {
         const buttplugDeviceMock = mock<ButtplugClientDevice>();
 
         const rangeAttrName: ButtplugIoDeviceAttributeKey = 'Vibrate-2';
-        const rangeAttr = IntRangeDeviceAttribute.create(
+        const rangeAttr = IntRangeDeviceAttribute.createInitialized(
             rangeAttrName,
             undefined,
             DeviceAttributeModifier.readWrite,
@@ -83,6 +84,7 @@ describe('ButtplugIoDevice', () => {
             Int.ZERO,
             Int.from(20),
             Int.from(1),
+            Int.ZERO,
         );
 
         const device = createDevice(
@@ -111,7 +113,7 @@ describe('ButtplugIoDevice', () => {
         // Arrange
         const buttplugDeviceMock = mock<ButtplugClientDevice>();
         const boolAttrKey: ButtplugIoDeviceAttributeKey = 'Rotate-1';
-        const boolAttr = BoolDeviceAttribute.create(boolAttrKey, undefined, DeviceAttributeModifier.readWrite);
+        const boolAttr = BoolDeviceAttribute.createInitialized(boolAttrKey, undefined, DeviceAttributeModifier.readWrite, false);
         const device = createDevice(buttplugDeviceMock, {[boolAttrKey]: boolAttr});
 
         // Act
@@ -128,7 +130,7 @@ describe('ButtplugIoDevice', () => {
         // Arrange
         const buttplugDeviceMock = mock<ButtplugClientDevice>();
         const attrKey: ButtplugIoDeviceAttributeKey = 'Vibrate-1';
-        const readOnlyAttr = BoolDeviceAttribute.create(attrKey, undefined, DeviceAttributeModifier.readOnly);
+        const readOnlyAttr = BoolDeviceAttribute.createInitialized(attrKey, undefined, DeviceAttributeModifier.readOnly, false);
         const device = createDevice(buttplugDeviceMock, {[attrKey]: readOnlyAttr});
 
         // Act
@@ -144,7 +146,7 @@ describe('ButtplugIoDevice', () => {
         // Arrange
         const buttplugDeviceMock = mock<ButtplugClientDevice>();
         const sensorAttrKey: ButtplugIoDeviceAttributeKey = 'Battery-1';
-        const attr = BoolDeviceAttribute.create(sensorAttrKey, undefined, DeviceAttributeModifier.readWrite);
+        const attr = BoolDeviceAttribute.createInitialized(sensorAttrKey, undefined, DeviceAttributeModifier.readWrite, false);
         const device = createDevice(buttplugDeviceMock, {[sensorAttrKey]: attr});
 
         // Act
@@ -160,11 +162,16 @@ describe('ButtplugIoDevice', () => {
         // Arrange
         const buttplugDeviceMock = mock<ButtplugClientDevice>();
         const attrKey: ButtplugIoDeviceAttributeKey = 'Vibrate-1';
-        const attr = BoolDeviceAttribute.create(attrKey, undefined, DeviceAttributeModifier.readWrite);
+        const attr = BoolDeviceAttribute.createInitialized(attrKey, undefined, DeviceAttributeModifier.readWrite, false);
         const device = createDevice(buttplugDeviceMock, {[attrKey]: attr});
 
+        // Go through the untyped device interface: this exercises the runtime guard that protects
+        // against callers (e.g. automation scripts) that aren't bound by the typed setAttribute
+        // overload, since TypeScript itself now rejects `undefined` here for a typed attribute.
+        const untypedDevice: AnyDevice = device;
+
         // Act
-        const result = device.setAttribute(attrKey, undefined);
+        const result = untypedDevice.setAttribute(attrKey, undefined);
 
         // Assert
         await expect(result).rejects.toThrow(`Value to be set for attribute '${attrKey}' cannot be undefined`);
diff --git a/tests/unit/device/protocol/estim2b/estim2bDevice.spec.ts b/tests/unit/device/protocol/estim2b/estim2bDevice.spec.ts
index f8af4212..03a69012 100644
--- a/tests/unit/device/protocol/estim2b/estim2bDevice.spec.ts
+++ b/tests/unit/device/protocol/estim2b/estim2bDevice.spec.ts
@@ -49,12 +49,12 @@ describe('EStim2bDevice', () => {
         ];
 
         return {
-            mode: ListDeviceAttribute.create<Int, string>('mode', 'Mode', DeviceAttributeModifier.readWrite, modeOptions),
-            channelALevel: IntRangeDeviceAttribute.create('channelALevel', 'Channel A', DeviceAttributeModifier.readWrite, undefined, Int.ZERO, Int.from(99), Int.from(1)),
-            channelBLevel: IntRangeDeviceAttribute.create('channelBLevel', 'Channel B', DeviceAttributeModifier.readWrite, undefined, Int.ZERO, Int.from(99), Int.from(1)),
-            channelsJoined: BoolDeviceAttribute.create('channelsJoined', 'Channels Joined', DeviceAttributeModifier.readOnly),
-            highPowerMode: BoolDeviceAttribute.create('highPowerMode', 'High Power Mode', DeviceAttributeModifier.readWrite),
-            batteryStatus: StrDeviceAttribute.create('batteryStatus', 'Battery', DeviceAttributeModifier.readOnly),
+            mode: ListDeviceAttribute.createInitialized<Int, string>('mode', 'Mode', DeviceAttributeModifier.readWrite, modeOptions, Int.from(EStim2bMode.pulse)),
+            channelALevel: IntRangeDeviceAttribute.createInitialized('channelALevel', 'Channel A', DeviceAttributeModifier.readWrite, undefined, Int.ZERO, Int.from(99), Int.from(1), Int.ZERO),
+            channelBLevel: IntRangeDeviceAttribute.createInitialized('channelBLevel', 'Channel B', DeviceAttributeModifier.readWrite, undefined, Int.ZERO, Int.from(99), Int.from(1), Int.ZERO),
+            channelsJoined: BoolDeviceAttribute.createInitialized('channelsJoined', 'Channels Joined', DeviceAttributeModifier.readOnly, false),
+            highPowerMode: BoolDeviceAttribute.createInitialized('highPowerMode', 'High Power Mode', DeviceAttributeModifier.readWrite, false),
+            batteryStatus: StrDeviceAttribute.createInitialized('batteryStatus', 'Battery', DeviceAttributeModifier.readOnly, ''),
         };
     }
 
diff --git a/tests/unit/device/protocol/zc95/zc95Device.spec.ts b/tests/unit/device/protocol/zc95/zc95Device.spec.ts
index f1a625ab..c82ba28c 100644
--- a/tests/unit/device/protocol/zc95/zc95Device.spec.ts
+++ b/tests/unit/device/protocol/zc95/zc95Device.spec.ts
@@ -60,8 +60,11 @@ describe('Zc95Device', () => {
     }
 
     function createPowerChannelAttrs(): Zc95DevicePowerChannelAttributes {
-        const makeAttr = (ch: number) =>
-            IntRangeDeviceAttribute.createInitialized(
+        // Power channel attributes are constructed unset in production (see
+        // Zc95Device.getChannelPowerAttribute()) and only get a value once a power status
+        // message has been received, so we mirror that here rather than using createInitialized().
+        const makeAttr = (ch: number) => {
+            const attr = IntRangeDeviceAttribute.create(
                 `powerChannel${ch}`,
                 `Channel ${ch}`,
                 DeviceAttributeModifier.readWrite,
@@ -69,8 +72,10 @@ describe('Zc95Device', () => {
                 Int.ZERO,
                 Int.from(100),
                 Int.from(1),
-                Int.from(10),
             );
+            attr.value = Int.from(10);
+            return attr;
+        };
 
         return {
             powerChannel1: makeAttr(1),
@@ -693,7 +698,7 @@ describe('Zc95Device', () => {
             mockProtocol.decode.mockReturnValue({ message: powerStatusMsg });
 
             const overLimitAttrs = createPowerChannelAttrs();
-            overLimitAttrs.powerChannel1 = IntRangeDeviceAttribute.createInitialized(
+            overLimitAttrs.powerChannel1 = IntRangeDeviceAttribute.create(
                 'powerChannel1',
                 'Channel 1',
                 DeviceAttributeModifier.readWrite,
@@ -701,8 +706,8 @@ describe('Zc95Device', () => {
                 Int.ZERO,
                 Int.from(100),
                 Int.from(1),
-                Int.from(90), // current value 90 was above the new power limit of 70
             );
+            overLimitAttrs.powerChannel1.value = Int.from(90); // current value 90 was above the new power limit of 70
 
             const device = createDevice({
                 activePattern: createActivePatternAttr(),