diff --git a/app/build.gradle b/app/build.gradle
index 07a7f3d90..29740eed6 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -42,9 +42,6 @@ android {
         }
     }
 
-    dexOptions {
-    }
-
     flavorDimensions "version"
     productFlavors {
         libre {
@@ -88,20 +85,23 @@ android {
         targetCompatibility JavaVersion.VERSION_1_8
         sourceCompatibility JavaVersion.VERSION_1_8
     }
+
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
 }
 
 def room_version = "2.2.5"
 
 dependencies {
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
     implementation 'androidx.appcompat:appcompat:1.1.0'
     implementation 'androidx.preference:preference:1.1.1'
-    implementation 'androidx.legacy:legacy-preference-v14:1.0.0'
     implementation 'androidx.cardview:cardview:1.0.0'
     implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
     implementation 'androidx.documentfile:documentfile:1.0.1'
     implementation 'androidx.biometric:biometric:1.0.1'
-    implementation "androidx.core:core-ktx:1.2.0"
+    implementation 'androidx.core:core-ktx:1.2.0'
     // To upgrade with style
     implementation 'com.google.android.material:material:1.0.0'
     // Database
diff --git a/build.gradle b/build.gradle
index dd8b50e5a..6c0955471 100644
--- a/build.gradle
+++ b/build.gradle
@@ -3,14 +3,10 @@ buildscript {
     ext.kotlin_version = '1.3.72'
     repositories {
         jcenter()
-        maven {
-            url 'https://maven.google.com/'
-            name 'Google'
-        }
         google()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.6.3'
+        classpath 'com.android.tools.build:gradle:4.0.0'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }
@@ -22,3 +18,7 @@ allprojects {
         maven { url "https://jitpack.io" }
     }
 }
+
+task clean(type: Delete) {
+    delete rootProject.buildDir
+}
diff --git a/icon-pack-classic/build.gradle b/icon-pack-classic/build.gradle
index 203c14168..d69bda28a 100644
--- a/icon-pack-classic/build.gradle
+++ b/icon-pack-classic/build.gradle
@@ -7,15 +7,7 @@ android {
     defaultConfig {
         minSdkVersion 14
         targetSdkVersion 29
-        versionCode 1
-        versionName "1.0"
-    }
-
-    buildTypes {
-        release {
-            minifyEnabled false
-        }
     }
 
     resourcePrefix 'classic_'
-}
\ No newline at end of file
+}
diff --git a/icon-pack-material/build.gradle b/icon-pack-material/build.gradle
index 56d83946e..2c2a7b9fd 100644
--- a/icon-pack-material/build.gradle
+++ b/icon-pack-material/build.gradle
@@ -7,14 +7,6 @@ android {
     defaultConfig {
         minSdkVersion 14
         targetSdkVersion 29
-        versionCode 1
-        versionName "1.0"
-    }
-
-    buildTypes {
-        release {
-            minifyEnabled false
-        }
     }
 
     resourcePrefix 'material_'