diff --git a/build.gradle b/build.gradle
index 4e78a239..db131b22 100644
--- a/build.gradle
+++ b/build.gradle
@@ -42,9 +42,9 @@ ext {
   javaTargetCompatibility = JavaVersion.VERSION_1_7
 
   // Libraries
-  appcompat7Version = '23.0.0'
-  supportAnnotations = '23.0.0'
-  recyclerviewVersion = '23.0.0'
+  appcompat7Version = '23.0.1'
+  supportAnnotations = '23.0.1'
+  recyclerviewVersion = '23.0.1'
 
   // Libraries for samples
   fragmentargsVersion = '2.1.0'
diff --git a/mvp/src/main/java/com/hannesdorfmann/mosby/mvp/delegate/BaseMvpDelegateCallback.java b/mvp/src/main/java/com/hannesdorfmann/mosby/mvp/delegate/BaseMvpDelegateCallback.java
index 4b85605c..9421cc8a 100644
--- a/mvp/src/main/java/com/hannesdorfmann/mosby/mvp/delegate/BaseMvpDelegateCallback.java
+++ b/mvp/src/main/java/com/hannesdorfmann/mosby/mvp/delegate/BaseMvpDelegateCallback.java
@@ -17,6 +17,7 @@
 package com.hannesdorfmann.mosby.mvp.delegate;
 
 import android.app.Activity;
+import android.support.annotation.NonNull;
 import com.hannesdorfmann.mosby.mvp.MvpPresenter;
 import com.hannesdorfmann.mosby.mvp.MvpView;
 
@@ -39,7 +40,7 @@ public interface BaseMvpDelegateCallback<V extends MvpView, P extends MvpPresent
    *
    * @return the created presenter instance
    */
-  public P createPresenter();
+  @NonNull public P createPresenter();
 
   /**
    * Get the presenter. If null is returned, then a internally a new presenter instance gets
diff --git a/viewstate/src/main/java/com/hannesdorfmann/mosby/mvp/delegate/BaseMvpViewStateDelegateCallback.java b/viewstate/src/main/java/com/hannesdorfmann/mosby/mvp/delegate/BaseMvpViewStateDelegateCallback.java
index 017eddea..e3896293 100644
--- a/viewstate/src/main/java/com/hannesdorfmann/mosby/mvp/delegate/BaseMvpViewStateDelegateCallback.java
+++ b/viewstate/src/main/java/com/hannesdorfmann/mosby/mvp/delegate/BaseMvpViewStateDelegateCallback.java
@@ -16,6 +16,7 @@
 
 package com.hannesdorfmann.mosby.mvp.delegate;
 
+import android.support.annotation.NonNull;
 import android.support.v4.app.Fragment;
 import com.hannesdorfmann.mosby.mvp.MvpPresenter;
 import com.hannesdorfmann.mosby.mvp.MvpView;
@@ -46,10 +47,11 @@ public interface BaseMvpViewStateDelegateCallback<V extends MvpView, P extends M
   /**
    * Create the viewstate. Will be called by the {@link MvpViewStateInternalDelegate}.
    */
-  public ViewState<V> createViewState();
+  @NonNull public ViewState<V> createViewState();
 
   /**
-   * This method will be called by {@link MvpViewStateInternalDelegate} to inform that restoring the view state
+   * This method will be called by {@link MvpViewStateInternalDelegate} to inform that restoring the
+   * view state
    * is in progress.
    *
    * @param restoringViewState true, if restoring viewstate is in progress, otherwise false