diff --git a/src/adapters/adapter.ts b/src/adapters/adapter.ts
index 2ee53025..17b991e0 100644
--- a/src/adapters/adapter.ts
+++ b/src/adapters/adapter.ts
@@ -23,26 +23,45 @@
 * SOFTWARE.
 */
 
-import type { BluetoothDevice } from '../device';
-import type { BluetoothRemoteGATTService } from '../service';
-import type { BluetoothRemoteGATTCharacteristic } from '../characteristic';
-import type { BluetoothRemoteGATTDescriptor } from '../descriptor';
+export interface BluetoothDeviceInit {
+    id: string;
+    name: string;
+    _serviceUUIDs: Array<string>;
+    _adData: Partial<BluetoothAdvertisingEvent>;
+}
+
+export interface BluetoothRemoteGATTServiceInit {
+    _handle: string;
+    uuid: string;
+    isPrimary: boolean;
+}
+
+export interface BluetoothRemoteGATTCharacteristicInit {
+    _handle: string;
+    uuid: string;
+    properties: BluetoothCharacteristicProperties;
+}
+
+export interface BluetoothRemoteGATTDescriptorInit {
+    _handle: string;
+    uuid: string;
+}
 
 /**
  * @hidden
  */
 export interface Adapter extends EventTarget {
     getEnabled: () => Promise<boolean>;
-    getAdapters: () => Array<{ index: number, address: string, active: boolean}>;
+    getAdapters: () => Array<{ index: number, address: string, active: boolean }>;
     useAdapter: (index: number) => void;
-    startScan: (serviceUUIDs: Array<string>, foundFn: (device: Partial<BluetoothDevice>) => void) => Promise<void>;
+    startScan: (serviceUUIDs: Array<string>, foundFn: (device: BluetoothDeviceInit) => void) => Promise<void>;
     stopScan: () => void;
     connect: (handle: string, disconnectFn?: () => void) => Promise<void>;
     disconnect: (handle: string) => Promise<void>;
-    discoverServices: (handle: string, serviceUUIDs?: Array<string>) => Promise<Array<Partial<BluetoothRemoteGATTService>>>;
-    discoverIncludedServices: (handle: string, serviceUUIDs?: Array<string>) => Promise<Array<Partial<BluetoothRemoteGATTService>>>;
-    discoverCharacteristics: (handle: string, characteristicUUIDs?: Array<string>) => Promise<Array<Partial<BluetoothRemoteGATTCharacteristic>>>;
-    discoverDescriptors: (handle: string, descriptorUUIDs?: Array<string>) => Promise<Array<Partial<BluetoothRemoteGATTDescriptor>>>;
+    discoverServices: (handle: string, serviceUUIDs?: Array<string>) => Promise<Array<BluetoothRemoteGATTServiceInit>>;
+    discoverIncludedServices: (handle: string, serviceUUIDs?: Array<string>) => Promise<Array<BluetoothRemoteGATTServiceInit>>;
+    discoverCharacteristics: (handle: string, characteristicUUIDs?: Array<string>) => Promise<Array<BluetoothRemoteGATTCharacteristicInit>>;
+    discoverDescriptors: (handle: string, descriptorUUIDs?: Array<string>) => Promise<Array<BluetoothRemoteGATTDescriptorInit>>;
     readCharacteristic: (handle: string) => Promise<DataView>;
     writeCharacteristic: (handle: string, value: DataView, withoutResponse?: boolean) => Promise<void>;
     enableNotify: (handle: string, notifyFn: (value: DataView) => void) => Promise<void>;
diff --git a/src/adapters/simpleble-adapter.ts b/src/adapters/simpleble-adapter.ts
index 65b7c483..e488ebed 100644
--- a/src/adapters/simpleble-adapter.ts
+++ b/src/adapters/simpleble-adapter.ts
@@ -23,12 +23,8 @@
 * SOFTWARE.
 */
 
-import { Adapter as BluetoothAdapter } from './adapter';
+import { Adapter as BluetoothAdapter, BluetoothDeviceInit, BluetoothRemoteGATTServiceInit, BluetoothRemoteGATTCharacteristicInit, BluetoothRemoteGATTDescriptorInit } from './adapter';
 import { BluetoothUUID } from '../uuid';
-import { BluetoothDevice } from '../device';
-import { BluetoothRemoteGATTCharacteristic } from '../characteristic';
-import { BluetoothRemoteGATTService } from '../service';
-import { BluetoothRemoteGATTDescriptor } from '../descriptor';
 import {
     isEnabled,
     getAdapters as simpleBleAdapters,
@@ -133,10 +129,23 @@ class PeripheralHandles {
         }
 
         const peripheralHandle = this.parents.get(serviceHandle);
+        if (!peripheralHandle) {
+            throw new Error('Peripheral not found for service');
+        }
+
+        const peripheral = this.peripherals.get(peripheralHandle);
+        if (!peripheral) {
+            throw new Error('Peripheral not found for service');
+        }
+
+        const service = this.services.get(serviceHandle);
+        if (!service) {
+            throw new Error('Service not found');
+        }
 
         return {
-            peripheral: this.peripherals.get(peripheralHandle!)!,
-            service: this.services.get(serviceHandle)!,
+            peripheral,
+            service,
             characteristics
         };
     }
@@ -159,25 +168,78 @@ class PeripheralHandles {
 
     public getCharacteristicGraph(characteristicHandle: string): { peripheral: Peripheral, service: Service, characteristic: Characteristic } {
         const serviceHandle = this.parents.get(characteristicHandle);
-        const peripheralHandle = this.parents.get(serviceHandle!);
+        if (!serviceHandle) {
+            throw new Error('Service not found for characteristic');
+        }
+
+        const peripheralHandle = this.parents.get(serviceHandle);
+        if (!peripheralHandle) {
+            throw new Error('Peripheral not found for characteristic');
+        }
+
+        const peripheral = this.peripherals.get(peripheralHandle);
+        if (!peripheral) {
+            throw new Error('Peripheral not found for characteristic');
+        }
+
+        const service = this.services.get(serviceHandle);
+        if (!service) {
+            throw new Error('Service not found for characteristic');
+        }
+
+        const characteristic = this.characteristics.get(characteristicHandle);
+        if (!characteristic) {
+            throw new Error('Characteristic not found');
+        }
 
         return {
-            peripheral: this.peripherals.get(peripheralHandle!)!,
-            service: this.services.get(serviceHandle!)!,
-            characteristic: this.characteristics.get(characteristicHandle)!
+            peripheral,
+            service,
+            characteristic
         };
     }
 
     public getDescriptorGraph(descriptorHandle: string): { peripheral: Peripheral, service: Service, characteristic: Characteristic, descriptor: Descriptor } {
         const characteristicHandle = this.parents.get(descriptorHandle);
-        const serviceHandle = this.parents.get(characteristicHandle!);
-        const peripheralHandle = this.parents.get(serviceHandle!);
+        if (!characteristicHandle) {
+            throw new Error('Characteristic not found for descriptor');
+        }
+
+        const serviceHandle = this.parents.get(characteristicHandle);
+        if (!serviceHandle) {
+            throw new Error('Service not found for descriptor');
+        }
+
+        const peripheralHandle = this.parents.get(serviceHandle);
+        if (!peripheralHandle) {
+            throw new Error('Peripheral not found for descriptor');
+        }
+
+        const peripheral = this.peripherals.get(peripheralHandle);
+        if (!peripheral) {
+            throw new Error('Peripheral not found for descriptor');
+        }
+
+        const service = this.services.get(serviceHandle);
+        if (!service) {
+            throw new Error('Service not found for descriptor');
+        }
+
+        const characteristic = this.characteristics.get(characteristicHandle);
+        if (!characteristic) {
+            throw new Error('Characteristic not found for descriptor');
+        }
+
+        const descriptor = this.descriptors.get(descriptorHandle);
+        if (!descriptor) {
+            throw new Error('Descriptor not found');
+        }
 
         return {
-            peripheral: this.peripherals.get(peripheralHandle!)!,
-            service: this.services.get(serviceHandle!)!,
-            characteristic: this.characteristics.get(characteristicHandle!)!,
-            descriptor: this.descriptors.get(descriptorHandle)!
+            peripheral,
+            service,
+            characteristic,
+            descriptor
         };
     }
 }
@@ -190,7 +252,7 @@ export class SimplebleAdapter extends EventTarget implements BluetoothAdapter {
     private peripherals = new Map<string, Peripheral>();
     private handles = new PeripheralHandles(this.peripherals);
 
-    private validDevice(device: Partial<BluetoothDevice>, serviceUUIDs: Array<string>): boolean {
+    private validDevice(device: BluetoothDeviceInit, serviceUUIDs: Array<string>): boolean {
         if (serviceUUIDs.length === 0) {
             // Match any device
             return true;
@@ -207,13 +269,12 @@ export class SimplebleAdapter extends EventTarget implements BluetoothAdapter {
         return serviceUUIDs.some(serviceUUID => advertisedUUIDs.indexOf(serviceUUID) >= 0);
     }
 
-    private buildBluetoothDevice(device: Peripheral): Partial<BluetoothDevice> {
+    private buildBluetoothDevice(device: Peripheral): BluetoothDeviceInit {
         const name = device.identifier;
         const address = device.address;
 
         const rssi = device.rssi;
         const txPower = device.txPower;
-        const mtu = device.mtu;
 
         const id = address || `${name}`;
 
@@ -239,7 +300,6 @@ export class SimplebleAdapter extends EventTarget implements BluetoothAdapter {
             _adData: {
                 rssi,
                 txPower,
-                mtu,
                 serviceData,
                 manufacturerData
             }
@@ -269,7 +329,7 @@ export class SimplebleAdapter extends EventTarget implements BluetoothAdapter {
         this.adapter = selected;
     }
 
-    public async startScan(serviceUUIDs: Array<string>, foundFn: (device: Partial<BluetoothDevice>) => void): Promise<void> {
+    public async startScan(serviceUUIDs: Array<string>, foundFn: (device: BluetoothDeviceInit) => void): Promise<void> {
         if (this.state === false) {
             throw new Error('adapter not enabled');
         }
@@ -282,9 +342,9 @@ export class SimplebleAdapter extends EventTarget implements BluetoothAdapter {
         this.adapter.setCallbackOnScanFound(peripheral => {
             const device = this.buildBluetoothDevice(peripheral);
             if (this.validDevice(device, serviceUUIDs)) {
-                if (!foundPeripherals.includes(device.id!)) {
-                    foundPeripherals.push(device.id!);
-                    this.peripherals.set(device.id!, peripheral);
+                if (!foundPeripherals.includes(device.id)) {
+                    foundPeripherals.push(device.id);
+                    this.peripherals.set(device.id, peripheral);
                     // Only call the found function the first time we find a valid device
                     foundFn(device);
                 }
@@ -343,10 +403,10 @@ export class SimplebleAdapter extends EventTarget implements BluetoothAdapter {
         this.handles.deleteHandles(peripheral);
     }
 
-    public async discoverServices(handle: string, serviceUUIDs?: Array<string>): Promise<Array<Partial<BluetoothRemoteGATTService>>> {
+    public async discoverServices(handle: string, serviceUUIDs?: Array<string>): Promise<Array<BluetoothRemoteGATTServiceInit>> {
         const services = this.handles.getServices(handle);
 
-        const discovered: Partial<BluetoothRemoteGATTService>[] = [];
+        const discovered: BluetoothRemoteGATTServiceInit[] = [];
         for (const [handle, service] of Object.entries(services)) {
             if (!serviceUUIDs || serviceUUIDs.length === 0 || serviceUUIDs.indexOf(service.uuid) >= 0) {
                 discovered.push({
@@ -360,15 +420,15 @@ export class SimplebleAdapter extends EventTarget implements BluetoothAdapter {
         return discovered;
     }
 
-    public async discoverIncludedServices(_handle: string, _serviceUUIDs?: Array<string>): Promise<Array<Partial<BluetoothRemoteGATTService>>> {
+    public async discoverIncludedServices(_handle: string, _serviceUUIDs?: Array<string>): Promise<Array<BluetoothRemoteGATTServiceInit>> {
         // Currently not implemented
         return [];
     }
 
-    public async discoverCharacteristics(handle: string, characteristicUUIDs?: Array<string>): Promise<Array<Partial<BluetoothRemoteGATTCharacteristic>>> {
+    public async discoverCharacteristics(handle: string, characteristicUUIDs?: Array<string>): Promise<Array<BluetoothRemoteGATTCharacteristicInit>> {
         const { peripheral, service, characteristics } = this.handles.getCharacteristics(handle);
 
-        const discovered: Partial<BluetoothRemoteGATTCharacteristic>[] = [];
+        const discovered: BluetoothRemoteGATTCharacteristicInit[] = [];
 
         for (const [handle, characteristic] of Object.entries(characteristics)) {
             const charUUID = BluetoothUUID.canonicalUUID(characteristic.uuid);
@@ -395,8 +455,10 @@ export class SimplebleAdapter extends EventTarget implements BluetoothAdapter {
                 if (characteristic.canIndicate) {
                     peripheral.indicate(service.uuid, charUUID, data => {
                         if (this.handles.characteristicEvents.has(handle)) {
-                            // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-                            this.handles.characteristicEvents.get(handle)!(new DataView(data.buffer));
+                            const event = this.handles.characteristicEvents.get(handle);
+                            if (event) {
+                                event(new DataView(data.buffer));
+                            }
                         }
                     });
                 }
@@ -404,8 +466,10 @@ export class SimplebleAdapter extends EventTarget implements BluetoothAdapter {
                 if (characteristic.canNotify) {
                     peripheral.notify(service.uuid, charUUID, data => {
                         if (this.handles.characteristicEvents.has(handle)) {
-                            // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-                            this.handles.characteristicEvents.get(handle)!(new DataView(data.buffer));
+                            const event = this.handles.characteristicEvents.get(handle);
+                            if (event) {
+                                event(new DataView(data.buffer));
+                            }
                         }
                     });
                 }
@@ -415,9 +479,9 @@ export class SimplebleAdapter extends EventTarget implements BluetoothAdapter {
         return discovered;
     }
 
-    public async discoverDescriptors(handle: string, descriptorUUIDs?: Array<string>): Promise<Array<Partial<BluetoothRemoteGATTDescriptor>>> {
+    public async discoverDescriptors(handle: string, descriptorUUIDs?: Array<string>): Promise<Array<BluetoothRemoteGATTDescriptorInit>> {
         const descriptors = this.handles.getDescriptors(handle);
-        const discovered = [];
+        const discovered = new Array<BluetoothRemoteGATTDescriptorInit>();
 
         for (const [handle, descriptor] of Object.entries(descriptors)) {
             const descUUID = BluetoothUUID.canonicalUUID(descriptor);
diff --git a/src/bluetooth.ts b/src/bluetooth.ts
index 8cfa3329..fe738d5e 100644
--- a/src/bluetooth.ts
+++ b/src/bluetooth.ts
@@ -24,6 +24,7 @@
 */
 
 import { adapter, EVENT_ENABLED } from './adapters';
+import { BluetoothDeviceInit } from './adapters/adapter';
 import { BluetoothDevice } from './device';
 import { BluetoothUUID } from './uuid';
 
@@ -190,7 +191,7 @@ class BluetoothImpl extends EventTarget implements Bluetooth {
         }
     }
 
-    private filterDevice(filters: Array<BluetoothLEScanFilter>, deviceInfo: Partial<BluetoothDevice>, validServices: string[]): Partial<BluetoothDevice> | undefined {
+    private filterDevice(filters: Array<BluetoothLEScanFilter>, deviceInfo: BluetoothDeviceInit, validServices: string[]): BluetoothDeviceInit | undefined {
         let valid = false;
 
         filters.forEach(filter => {
@@ -207,7 +208,7 @@ class BluetoothImpl extends EventTarget implements Bluetooth {
             if (filter.services) {
                 const serviceUUIDs = filter.services.map(BluetoothUUID.getService);
                 const servicesValid = serviceUUIDs.every(serviceUUID => {
-                    return (deviceInfo._serviceUUIDs!.indexOf(serviceUUID) > -1);
+                    return (deviceInfo._serviceUUIDs.indexOf(serviceUUID) > -1);
                 });
 
                 if (!servicesValid) return;
@@ -216,7 +217,7 @@ class BluetoothImpl extends EventTarget implements Bluetooth {
 
             // Service Data
             if (filter.serviceData) {
-                if (!deviceInfo._adData?.serviceData) return;
+                if (!deviceInfo._adData.serviceData) return;
                 const services = [...deviceInfo._adData.serviceData.keys()];
                 for (const entry of filter.serviceData) {
                     if (!services.includes(entry.service)) return;
@@ -225,7 +226,7 @@ class BluetoothImpl extends EventTarget implements Bluetooth {
 
             // Manufacturer Data
             if (filter.manufacturerData) {
-                if (!deviceInfo._adData?.manufacturerData) return;
+                if (!deviceInfo._adData.manufacturerData) return;
                 const manufacturers = [...deviceInfo._adData.manufacturerData.keys()];
                 for (const entry of filter.manufacturerData) {
                     if (!manufacturers.includes(entry.companyIdentifier)) return;
@@ -351,12 +352,8 @@ class BluetoothImpl extends EventTarget implements Bluetooth {
                     const allowedServices = validServices.filter((item, index, array) => {
                         return array.indexOf(item) === index;
                     });
-                    Object.assign(deviceInfo, {
-                        _bluetooth: this,
-                        _allowedServices: allowedServices
-                    });
 
-                    const bluetoothDevice = new BluetoothDevice(deviceInfo, () => this.forgetDevice(deviceInfo.id!));
+                    const bluetoothDevice = new BluetoothDevice(deviceInfo, this, allowedServices, () => this.forgetDevice(deviceInfo.id));
 
                     const selectFn = () => {
                         complete.call(this, bluetoothDevice);
@@ -388,13 +385,8 @@ class BluetoothImpl extends EventTarget implements Bluetooth {
             }, this.scanTime);
 
             adapter.startScan([], deviceInfo => {
-                if (this.options?.allowAllDevices || this.allowedDevices.has(deviceInfo.id!)) {
-                    Object.assign(deviceInfo, {
-                        _bluetooth: this,
-                        _allowedServices: []
-                    });
-
-                    const bluetoothDevice = new BluetoothDevice(deviceInfo, () => this.forgetDevice(deviceInfo.id!));
+                if (this.options.allowAllDevices || this.allowedDevices.has(deviceInfo.id)) {
+                    const bluetoothDevice = new BluetoothDevice(deviceInfo, this, [], () => this.forgetDevice(deviceInfo.id));
                     devices.push(bluetoothDevice);
                 }
             });
diff --git a/src/characteristic.ts b/src/characteristic.ts
index a4d0e573..ad29ecf6 100644
--- a/src/characteristic.ts
+++ b/src/characteristic.ts
@@ -27,6 +27,7 @@ import { adapter } from './adapters';
 import { BluetoothRemoteGATTDescriptor } from './descriptor';
 import { BluetoothUUID } from './uuid';
 import { BluetoothRemoteGATTService } from './service';
+import { BluetoothRemoteGATTCharacteristicInit } from './adapters/adapter';
 
 const isView = (source: ArrayBuffer | ArrayBufferView): source is ArrayBufferView => (source as ArrayBufferView).buffer !== undefined;
 
@@ -56,7 +57,7 @@ class BluetoothRemoteGATTCharacteristicImpl extends EventTarget implements Bluet
      */
     public readonly properties: BluetoothCharacteristicProperties;
 
-    private _value: DataView;
+    private _value: DataView = new DataView(new ArrayBuffer(0));
     /**
      * The value of the characteristic
      */
@@ -86,14 +87,13 @@ class BluetoothRemoteGATTCharacteristicImpl extends EventTarget implements Bluet
      * Characteristic constructor
      * @param init A partial class to initialise values
      */
-    constructor(init: Partial<BluetoothRemoteGATTCharacteristicImpl>) {
+    constructor(init: BluetoothRemoteGATTCharacteristicInit, service: BluetoothRemoteGATTService) {
         super();
 
-        this.service = init.service!;
-        this.uuid = init.uuid!;
-        this.properties = init.properties!;
-        this._value = init.value!;
-        this._handle = init._handle!;
+        this.service = service;
+        this.uuid = init.uuid;
+        this.properties = init.properties;
+        this._handle = init._handle;
     }
 
     private setValue(value?: DataView, emit?: boolean) {
@@ -143,10 +143,7 @@ class BluetoothRemoteGATTCharacteristicImpl extends EventTarget implements Bluet
         if (!this.descriptors) {
             const descriptors = await adapter.discoverDescriptors(this._handle);
             this.descriptors = descriptors.map(descriptorInfo => {
-                Object.assign(descriptorInfo, {
-                    characteristic: this
-                });
-                return new BluetoothRemoteGATTDescriptor(descriptorInfo);
+                return new BluetoothRemoteGATTDescriptor(descriptorInfo, this);
             });
         }
 
@@ -228,7 +225,7 @@ class BluetoothRemoteGATTCharacteristicImpl extends EventTarget implements Bluet
      * Start notifications of changes for the characteristic
      * @returns Promise containing the characteristic
      */
-    public async startNotifications(): Promise<BluetoothRemoteGATTCharacteristicImpl> {
+    public async startNotifications(): Promise<BluetoothRemoteGATTCharacteristic> {
         if (!this.service.device.gatt.connected) {
             throw new Error('startNotifications error: device not connected');
         }
@@ -244,7 +241,7 @@ class BluetoothRemoteGATTCharacteristicImpl extends EventTarget implements Bluet
      * Stop notifications of changes for the characteristic
      * @returns Promise containing the characteristic
      */
-    public async stopNotifications(): Promise<BluetoothRemoteGATTCharacteristicImpl> {
+    public async stopNotifications(): Promise<BluetoothRemoteGATTCharacteristic> {
         if (!this.service.device.gatt.connected) {
             throw new Error('stopNotifications error: device not connected');
         }
diff --git a/src/descriptor.ts b/src/descriptor.ts
index b67eaca1..7c4ff583 100644
--- a/src/descriptor.ts
+++ b/src/descriptor.ts
@@ -24,6 +24,7 @@
 */
 
 import { adapter } from './adapters';
+import { BluetoothRemoteGATTDescriptorInit } from './adapters/adapter';
 
 /**
  * Bluetooth Remote GATT Descriptor class
@@ -40,7 +41,7 @@ class BluetoothRemoteGATTDescriptorImpl implements BluetoothRemoteGATTDescriptor
      */
     public readonly uuid: string;
 
-    private _value: DataView;
+    private _value: DataView = new DataView(new ArrayBuffer(0));
     /**
      * The value of the descriptor
      */
@@ -57,11 +58,10 @@ class BluetoothRemoteGATTDescriptorImpl implements BluetoothRemoteGATTDescriptor
      * Descriptor constructor
      * @param init A partial class to initialise values
      */
-    constructor(init: Partial<BluetoothRemoteGATTDescriptorImpl>) {
-        this.characteristic = init.characteristic!;
-        this.uuid = init.uuid!;
-        this._value = init.value!;
-        this._handle = init._handle!;
+    constructor(init: BluetoothRemoteGATTDescriptorInit, characteristic: BluetoothRemoteGATTCharacteristic) {
+        this.characteristic = characteristic;
+        this.uuid = init.uuid;
+        this._handle = init._handle;
     }
 
     /**
diff --git a/src/device.ts b/src/device.ts
index 508edb36..4e0ec82e 100644
--- a/src/device.ts
+++ b/src/device.ts
@@ -23,6 +23,7 @@
 * SOFTWARE.
 */
 
+import { BluetoothDeviceInit } from './adapters/adapter';
 import { BluetoothRemoteGATTServer } from './server';
 
 /**
@@ -163,20 +164,18 @@ class BluetoothDeviceImpl extends EventTarget implements BluetoothDevice {
      * Device constructor
      * @param init A partial class to initialise values
      */
-    constructor(init: Partial<BluetoothDeviceImpl>, private forgetFn: () => void) {
+    constructor(init: BluetoothDeviceInit, bluetooth: Bluetooth, allowedServices: string[], private forgetFn: () => void) {
         super();
 
-        this.id = init.id!;
-        this.name = init.name!;
-        this.gatt = init.gatt!;
+        this.id = init.id;
+        this.name = init.name || `Unknown or Unsupported Device (${this.id})`;
 
-        this._adData = init._adData!;
-        this._bluetooth = init._bluetooth!;
-        this._allowedServices = init._allowedServices!;
-        this._serviceUUIDs = init._serviceUUIDs!;
+        this._adData = init._adData;
+        this._bluetooth = bluetooth;
+        this._allowedServices = allowedServices;
+        this._serviceUUIDs = init._serviceUUIDs;
 
-        if (!this.name) this.name = `Unknown or Unsupported Device (${this.id})`;
-        if (!this.gatt) this.gatt = new BluetoothRemoteGATTServer(this);
+        this.gatt = new BluetoothRemoteGATTServer(this);
     }
 
     /**
diff --git a/src/server.ts b/src/server.ts
index 6219c07b..a159263b 100644
--- a/src/server.ts
+++ b/src/server.ts
@@ -124,10 +124,7 @@ class BluetoothRemoteGATTServerImpl implements BluetoothRemoteGATTServer {
         if (!this.services) {
             const services = await adapter.discoverServices(this._handle, this.device._allowedServices);
             this.services = services.map(serviceInfo => {
-                Object.assign(serviceInfo, {
-                    device: this.device
-                });
-                return new BluetoothRemoteGATTService(serviceInfo);
+                return new BluetoothRemoteGATTService(serviceInfo, this.device);
             });
         }
 
diff --git a/src/service.ts b/src/service.ts
index d37521c8..55c1c109 100644
--- a/src/service.ts
+++ b/src/service.ts
@@ -27,6 +27,7 @@ import { adapter } from './adapters';
 import { BluetoothDevice } from './device';
 import { BluetoothRemoteGATTCharacteristic } from './characteristic';
 import { BluetoothUUID } from './uuid';
+import { BluetoothRemoteGATTServiceInit } from './adapters/adapter';
 
 /**
  * Bluetooth Remote GATT Service class
@@ -117,13 +118,13 @@ class BluetoothRemoteGATTServiceImpl extends EventTarget implements BluetoothRem
      * Service constructor
      * @param init A partial class to initialise values
      */
-    constructor(init: Partial<BluetoothRemoteGATTServiceImpl>) {
+    constructor(init: BluetoothRemoteGATTServiceInit, device: BluetoothDevice) {
         super();
 
-        this.device = init.device!;
-        this.uuid = init.uuid!;
-        this.isPrimary = init.isPrimary!;
-        this._handle = init._handle!;
+        this.device = device;
+        this.uuid = init.uuid;
+        this.isPrimary = init.isPrimary;
+        this._handle = init._handle;
 
         this.dispatchEvent(new CustomEvent('serviceadded', { bubbles: true }));
         this.device.dispatchEvent(new CustomEvent('serviceadded', { bubbles: true }));
@@ -165,10 +166,7 @@ class BluetoothRemoteGATTServiceImpl extends EventTarget implements BluetoothRem
         if (!this.characteristics) {
             const characteristics = await adapter.discoverCharacteristics(this._handle);
             this.characteristics = characteristics.map(characteristicInfo => {
-                Object.assign(characteristicInfo, {
-                    service: this
-                });
-                return new BluetoothRemoteGATTCharacteristic(characteristicInfo);
+                return new BluetoothRemoteGATTCharacteristic(characteristicInfo, this);
             });
         }
 
@@ -223,10 +221,7 @@ class BluetoothRemoteGATTServiceImpl extends EventTarget implements BluetoothRem
         if (!this.services) {
             const services = await adapter.discoverIncludedServices(this._handle, this.device._allowedServices);
             this.services = services.map(serviceInfo => {
-                Object.assign(serviceInfo, {
-                    device: this.device
-                });
-                return new BluetoothRemoteGATTServiceImpl(serviceInfo);
+                return new BluetoothRemoteGATTServiceImpl(serviceInfo, this.device);
             });
         }
 
diff --git a/tsconfig.json b/tsconfig.json
index 34175eca..8ac3cdd8 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,7 +1,7 @@
 {
     "compilerOptions": {
-        "target": "ES2017",
-        "module": "CommonJS",
+        "target": "es5",
+        "alwaysStrict": true,
         "strict": true,
         "downlevelIteration": true,
         "noImplicitReturns": true,