diff --git a/src/index.ts b/src/index.ts
index 16b567e..15e25d2 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -239,9 +239,9 @@ export default class Updater {
                 // check for error
 
                 // write file length
-                return new Promise((resolve, reject) => {
+                return new Promise(async (resolve, reject) => {
                         // set mtu
-                        this.bleObject.requestMtu(this.bleDeviceId, this._packetSize, (mtu: number) => { this._packetSize = mtu}, () =>{});
+                        this._packetSize = await this.bleObject.withPromises.requestMtu(this.bleDeviceId, this._packetSize);
                         // start notify
                         this.bleObject.startNotification(this.bleDeviceId, this._updaterServiceUUID, this._updaterCommandCharacterisitcUUID,
                                 (rawData: ArrayBuffer): void => {