diff --git a/app/build.gradle b/app/build.gradle
index 4c133eb..d16f606 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -1,21 +1,21 @@
 plugins {
-    id 'com.android.application'
-    id 'kotlin-android'
-    id 'kotlin-kapt'
+    id "com.android.application"
+    id "kotlin-android"
+    id "kotlin-kapt"
 }
 
 android {
-    compileSdkVersion 30
-    buildToolsVersion "30.0.3"
+    compileSdkVersion 31
+    buildToolsVersion "31.0.0"
 
     repositories {
-        maven { url 'https://jitpack.io' }
+        maven { url "https://jitpack.io" }
     }
 
     defaultConfig {
         applicationId "com.github.muellerma.prepaidbalance"
         minSdkVersion 26
-        targetSdkVersion 30
+        targetSdkVersion 31
         versionCode 9
         versionName "1.1"
 
@@ -25,7 +25,7 @@ android {
     buildTypes {
         release {
             minifyEnabled false
-            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+            proguardFiles getDefaultProguardFile("proguard-android-optimize.txt"), "proguard-rules.pro"
         }
     }
     lintOptions {
@@ -36,7 +36,7 @@ android {
         targetCompatibility JavaVersion.VERSION_1_8
     }
     kotlinOptions {
-        jvmTarget = '1.8'
+        jvmTarget = "1.8"
     }
     buildFeatures {
         viewBinding true
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index bd0d65d..0b7843c 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -11,7 +11,9 @@
         android:label="@string/app_name"
         android:supportsRtl="true"
         android:theme="@style/Theme.App">
-        <activity android:name="com.github.muellerma.prepaidbalance.ui.MainActivity">
+        <activity
+            android:name="com.github.muellerma.prepaidbalance.ui.MainActivity"
+            android:exported="true">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
 
diff --git a/build.gradle b/build.gradle
index 8d859b5..b2d5a9d 100644
--- a/build.gradle
+++ b/build.gradle
@@ -7,10 +7,10 @@ buildscript {
     repositories {
         google()
         mavenCentral()
-        maven { url 'https://jitpack.io' }
+        maven { url "https://jitpack.io" }
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:7.0.3'
+        classpath "com.android.tools.build:gradle:7.0.3"
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
 
         // NOTE: Do not place your application dependencies here; they belong