diff --git a/library/build.gradle b/library/build.gradle
index 91b65ca9..551c4333 100644
--- a/library/build.gradle
+++ b/library/build.gradle
@@ -20,8 +20,11 @@ android {
         }
     }
     compileOptions {
-        sourceCompatibility JavaVersion.VERSION_1_8
-        targetCompatibility JavaVersion.VERSION_1_8
+        sourceCompatibility = 1.8
+        targetCompatibility = 1.8
+    }
+    kotlinOptions {
+        jvmTarget = "1.8"
     }
 }
 
diff --git a/sample/build.gradle b/sample/build.gradle
index 551c59fd..22af1cd2 100644
--- a/sample/build.gradle
+++ b/sample/build.gradle
@@ -21,8 +21,11 @@ android {
         }
     }
     compileOptions {
-        sourceCompatibility JavaVersion.VERSION_1_8
-        targetCompatibility JavaVersion.VERSION_1_8
+        sourceCompatibility = 1.8
+        targetCompatibility = 1.8
+    }
+    kotlinOptions {
+        jvmTarget = "1.8"
     }
     androidExtensions {
         experimental true