diff --git a/opentasks-contract/build.gradle b/opentasks-contract/build.gradle
index 8fc36977f..f3a3d674c 100644
--- a/opentasks-contract/build.gradle
+++ b/opentasks-contract/build.gradle
@@ -18,8 +18,8 @@ android {
         }
     }
     compileOptions {
-        sourceCompatibility JavaVersion.VERSION_1_7
-        targetCompatibility JavaVersion.VERSION_1_7
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
     }
 }
 
diff --git a/opentasks-provider/build.gradle b/opentasks-provider/build.gradle
index a80a4a15a..2b600c052 100644
--- a/opentasks-provider/build.gradle
+++ b/opentasks-provider/build.gradle
@@ -18,8 +18,8 @@ android {
         }
     }
     compileOptions {
-        sourceCompatibility JavaVersion.VERSION_1_7
-        targetCompatibility JavaVersion.VERSION_1_7
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
     }
     packagingOptions {
         exclude 'META-INF/NOTICE'
diff --git a/opentasks/build.gradle b/opentasks/build.gradle
index e92762eb8..5b357783d 100644
--- a/opentasks/build.gradle
+++ b/opentasks/build.gradle
@@ -39,8 +39,8 @@ android {
         disable 'MissingTranslation' // TODO
     }
     compileOptions {
-        sourceCompatibility JavaVersion.VERSION_1_7
-        targetCompatibility JavaVersion.VERSION_1_7
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
     }
 }
 
diff --git a/opentasks/src/main/java/org/dmfs/tasks/homescreen/TaskListSelectionFragment.java b/opentasks/src/main/java/org/dmfs/tasks/homescreen/TaskListSelectionFragment.java
index 279b1d47d..2cdb551f9 100644
--- a/opentasks/src/main/java/org/dmfs/tasks/homescreen/TaskListSelectionFragment.java
+++ b/opentasks/src/main/java/org/dmfs/tasks/homescreen/TaskListSelectionFragment.java
@@ -27,7 +27,6 @@
 import android.support.v4.content.Loader;
 import android.view.LayoutInflater;
 import android.view.View;
-import android.view.View.OnClickListener;
 import android.view.ViewGroup;
 import android.widget.ListView;
 import android.widget.TextView;
@@ -88,29 +87,21 @@ public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle sa
         mButtonOk = (TextView) rootView.findViewById(android.R.id.button1);
         mButtonCancel = (TextView) rootView.findViewById(android.R.id.button2);
 
-        mButtonOk.setOnClickListener(new OnClickListener()
+        mButtonOk.setOnClickListener(v ->
         {
-            @Override
-            public void onClick(View v)
+            if (mListener != null)
             {
-                if (mListener != null)
-                {
-                    mListener.onSelection(mTaskListAdapter.getSelectedLists());
-                }
-
+                mListener.onSelection(mTaskListAdapter.getSelectedLists());
             }
+
         });
-        mButtonCancel.setOnClickListener(new OnClickListener()
+        mButtonCancel.setOnClickListener(v ->
         {
-            @Override
-            public void onClick(View v)
+            if (mListener != null)
             {
-                if (mListener != null)
-                {
-                    mListener.onSelectionCancel();
-                }
-
+                mListener.onSelectionCancel();
             }
+
         });
 
         return rootView;
diff --git a/opentaskspal/build.gradle b/opentaskspal/build.gradle
index b26cd85c1..733b02c3d 100644
--- a/opentaskspal/build.gradle
+++ b/opentaskspal/build.gradle
@@ -12,6 +12,10 @@ android {
         exclude 'META-INF/NOTICE'
         exclude 'META-INF/LICENSE'
     }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
 }
 
 dependencies {