diff --git a/OpenKeychain/build.gradle b/OpenKeychain/build.gradle
index 010a9a929..0a0b150ee 100644
--- a/OpenKeychain/build.gradle
+++ b/OpenKeychain/build.gradle
@@ -8,46 +8,46 @@ dependencies {
     // NOTE: libraries are pinned to a specific build, see below
 
     // from local Android SDK
-    compile 'com.android.support:support-v4:27.1.1'
-    compile 'com.android.support:appcompat-v7:27.1.1'
-    compile 'com.android.support:design:27.1.1'
-    compile 'com.android.support:recyclerview-v7:27.1.1'
-    compile 'com.android.support:cardview-v7:27.1.1'
-    compile 'com.android.support:support-annotations:27.1.1'
+    implementation 'com.android.support:support-v4:27.1.1'
+    implementation 'com.android.support:appcompat-v7:27.1.1'
+    implementation 'com.android.support:design:27.1.1'
+    implementation 'com.android.support:recyclerview-v7:27.1.1'
+    implementation 'com.android.support:cardview-v7:27.1.1'
+    implementation 'com.android.support:support-annotations:27.1.1'
 
     // JCenter etc.
-    compile 'com.journeyapps:zxing-android-embedded:3.4.0'
-    compile 'com.google.zxing:core:3.3.0'
-    compile 'org.commonjava.googlecode.markdown4j:markdown4j:2.2-cj-1.1'
-    compile 'org.sufficientlysecure:donations:2.5'
-    compile 'com.squareup.okhttp3:okhttp:3.9.1'
-    compile 'com.squareup.okhttp3:okhttp-urlconnection:3.9.1'
-    compile 'org.apache.james:apache-mime4j-core:0.8.0'
-    compile 'org.apache.james:apache-mime4j-dom:0.8.0'
+    implementation 'com.journeyapps:zxing-android-embedded:3.4.0'
+    implementation 'com.google.zxing:core:3.3.0'
+    implementation 'org.commonjava.googlecode.markdown4j:markdown4j:2.2-cj-1.1'
+    implementation 'org.sufficientlysecure:donations:2.5'
+    implementation 'com.squareup.okhttp3:okhttp:3.9.1'
+    implementation 'com.squareup.okhttp3:okhttp-urlconnection:3.9.1'
+    implementation 'org.apache.james:apache-mime4j-core:0.8.0'
+    implementation 'org.apache.james:apache-mime4j-dom:0.8.0'
 
     // UI
-    compile 'org.sufficientlysecure:html-textview:3.1'
-    compile 'com.jpardogo.materialtabstrip:library:1.1.1'
-    compile 'com.getbase:floatingactionbutton:1.10.1'
-    compile 'com.nispok:snackbar:2.11.0'
-    compile 'com.cocosw:bottomsheet:1.3.1@aar'
+    implementation 'org.sufficientlysecure:html-textview:3.1'
+    implementation 'com.jpardogo.materialtabstrip:library:1.1.1'
+    implementation 'com.getbase:floatingactionbutton:1.10.1'
+    implementation 'com.nispok:snackbar:2.11.0'
+    implementation 'com.cocosw:bottomsheet:1.3.1@aar'
 
     // RecyclerView
-    compile 'eu.davidea:flexible-adapter:5.0.5'
-    compile 'eu.davidea:flexible-adapter-ui:1.0.0-b5'
-    compile 'eu.davidea:flexible-adapter-livedata:1.0.0-b2'
+    implementation 'eu.davidea:flexible-adapter:5.0.5'
+    implementation 'eu.davidea:flexible-adapter-ui:1.0.0-b5'
+    implementation 'eu.davidea:flexible-adapter-livedata:1.0.0-b2'
 
     // Material Drawer
-    compile 'com.mikepenz:materialdrawer:5.6.0@aar'
-    compile 'com.mikepenz:fastadapter:1.8.2'
-    compile 'com.mikepenz:materialize:1.0.0'
-    compile 'com.mikepenz:iconics-core:2.8.1@aar'
-    compile 'com.mikepenz:google-material-typeface:2.2.0.3.original@aar'
-    compile 'com.mikepenz:fontawesome-typeface:4.6.0.3@aar'
-    compile 'com.mikepenz:community-material-typeface:1.5.54.2@aar'
+    implementation 'com.mikepenz:materialdrawer:5.6.0@aar'
+    implementation 'com.mikepenz:fastadapter:1.8.2'
+    implementation 'com.mikepenz:materialize:1.0.0'
+    implementation 'com.mikepenz:iconics-core:2.8.1@aar'
+    implementation 'com.mikepenz:google-material-typeface:2.2.0.3.original@aar'
+    implementation 'com.mikepenz:fontawesome-typeface:4.6.0.3@aar'
+    implementation 'com.mikepenz:community-material-typeface:1.5.54.2@aar'
 
     // Nordpol
-    compile 'com.fidesmo:nordpol-android:0.1.22'
+    implementation 'com.fidesmo:nordpol-android:0.1.22'
 
     // piwik
     implementation 'org.piwik.sdk:piwik-sdk:3.0.3'
@@ -92,25 +92,24 @@ dependencies {
         exclude module: 'recyclerview-v7'
     }
 
-    compile "com.jakewharton.timber:timber:4.5.1"
+    implementation "com.jakewharton.timber:timber:4.5.1"
 
-    compile 'org.glassfish:javax.annotation:10.0-b28'
+    implementation 'org.glassfish:javax.annotation:10.0-b28'
     provided    "com.google.auto.value:auto-value:1.5"
     annotationProcessor "com.google.auto.value:auto-value:1.5"
     annotationProcessor "com.ryanharter.auto.value:auto-value-parcel:0.2.5"
-    compile 'com.ryanharter.auto.value:auto-value-parcel-adapter:0.2.5'
+    implementation 'com.ryanharter.auto.value:auto-value-parcel-adapter:0.2.5'
 
-    compile "android.arch.lifecycle:extensions:1.0.0"
+    implementation "android.arch.lifecycle:extensions:1.0.0"
     annotationProcessor "android.arch.lifecycle:compiler:1.0.0"
 
-    compile "android.arch.persistence:db-framework:1.0.0"
+    implementation "android.arch.persistence:db-framework:1.0.0"
     implementation 'com.android.support.constraint:constraint-layout:1.1.3'
 
     // for debugging the db. don't enable by default, this will expose the database no the network!
     // debugImplementation 'com.amitshekhar.android:debug-db:1.0.3'
 }
 
-
 android {
     compileSdkVersion rootProject.ext.compileSdkVersion
     buildToolsVersion rootProject.ext.buildToolsVersion
diff --git a/build.gradle b/build.gradle
index 93f96959f..527117962 100644
--- a/build.gradle
+++ b/build.gradle
@@ -7,7 +7,6 @@ buildscript {
     dependencies {
         // NOTE: Always use fixed version codes not dynamic ones, e.g. 0.7.3 instead of 0.7.+, see README for more information
         classpath 'com.android.tools.build:gradle:3.1.4'
-        classpath files('gradle-witness.jar')
         // bintray dependency to satisfy dependency of openpgp-api lib
         classpath 'com.novoda:bintray-release:0.8.0'
         classpath 'com.squareup.sqldelight:gradle-plugin:0.7.0'