diff --git a/backdrop/build.gradle b/backdrop/build.gradle
index 7c975ad..3392390 100644
--- a/backdrop/build.gradle
+++ b/backdrop/build.gradle
@@ -37,11 +37,11 @@ subprojects {
 
 android {
 
-    compileSdkVersion 27
+    compileSdkVersion 28
 
     defaultConfig {
         minSdkVersion 21
-        targetSdkVersion 27
+        targetSdkVersion 28
     }
 
     buildTypes {
@@ -57,8 +57,8 @@ android {
 }
 
 ext {
-    supportVersion = '27.1.1'
-    kotlin_version = '1.2.41'
+    supportVersion = '28.0.0-rc01'
+    kotlin_version = '1.2.50'
 }
 
 dependencies {
diff --git a/backdrop/src/main/kotlin/ru/semper_viventem/backdrop/BackdropBehavior.kt b/backdrop/src/main/kotlin/ru/semper_viventem/backdrop/BackdropBehavior.kt
index 794e6fb..af85033 100644
--- a/backdrop/src/main/kotlin/ru/semper_viventem/backdrop/BackdropBehavior.kt
+++ b/backdrop/src/main/kotlin/ru/semper_viventem/backdrop/BackdropBehavior.kt
@@ -48,13 +48,13 @@ class BackdropBehavior : CoordinatorLayout.Behavior<View> {
 
     constructor(context: Context, attrs: AttributeSet) : super(context, attrs)
 
-    override fun onSaveInstanceState(parent: CoordinatorLayout?, child: View?): Parcelable {
+    override fun onSaveInstanceState(parent: CoordinatorLayout, child: View): Parcelable {
         return Bundle().apply {
             putSerializable(ARG_DROP_STATE, dropState)
         }
     }
 
-    override fun onRestoreInstanceState(parent: CoordinatorLayout?, child: View?, state: Parcelable?) {
+    override fun onRestoreInstanceState(parent: CoordinatorLayout, child: View, state: Parcelable) {
         super.onRestoreInstanceState(parent, child, state)
 
             dropState = (state as? Bundle)?.getSerializable(ARG_DROP_STATE) as? DropState ?: DEFAULT_DROP_STATE
diff --git a/sample/build.gradle b/sample/build.gradle
index d1df942..954e6e3 100644
--- a/sample/build.gradle
+++ b/sample/build.gradle
@@ -6,7 +6,7 @@ apply plugin: 'kotlin-kapt'
 
 android {
 
-    compileSdkVersion 'android-P'
+    compileSdkVersion 28
 
     defaultConfig {
         applicationId "ru.semper_viventem.backdropview"