diff --git a/build.gradle b/build.gradle
index 11fea2e..2ca0321 100644
--- a/build.gradle
+++ b/build.gradle
@@ -106,9 +106,12 @@ allprojects {
         onlyIf { isReleaseBuild() }
     }
 
-    tasks.withType(JavaCompile) {
-        sourceCompatibility = JavaVersion.VERSION_11
-        targetCompatibility = JavaVersion.VERSION_11
+    tasks.withType(JavaCompile).configureEach {
+        sourceCompatibility = JavaVersion.VERSION_1_8
+        targetCompatibility = JavaVersion.VERSION_1_8
+        if (JavaVersion.current().isJava9Compatible() && !project.plugins.hasPlugin('com.android.library')) {
+            options.release.set(8)
+        }
     }
 }
 
diff --git a/gdx-pay-android-amazon/build.gradle b/gdx-pay-android-amazon/build.gradle
index 1ab23e4..aac2c71 100644
--- a/gdx-pay-android-amazon/build.gradle
+++ b/gdx-pay-android-amazon/build.gradle
@@ -1,8 +1,8 @@
 apply plugin: 'com.android.library'
 apply from : '../publish_android.gradle'
 
-sourceCompatibility = 11
-targetCompatibility = 11
+sourceCompatibility = JavaVersion.VERSION_1_8
+targetCompatibility = JavaVersion.VERSION_1_8
 
 android {
     namespace 'com.badlogic.gdx.pay.android.amazon'
diff --git a/gdx-pay-client/build.gradle b/gdx-pay-client/build.gradle
index 0eb1977..7198070 100644
--- a/gdx-pay-client/build.gradle
+++ b/gdx-pay-client/build.gradle
@@ -1,8 +1,8 @@
 apply plugin : 'java-library'
 apply from : '../publish_java.gradle'
 
-sourceCompatibility = 11
-targetCompatibility = 11
+sourceCompatibility = JavaVersion.VERSION_1_8
+targetCompatibility = JavaVersion.VERSION_1_8
 
 sourceSets {
     main {
diff --git a/gdx-pay-iosrobovm-apple/build.gradle b/gdx-pay-iosrobovm-apple/build.gradle
index a825a0c..9ee3d21 100644
--- a/gdx-pay-iosrobovm-apple/build.gradle
+++ b/gdx-pay-iosrobovm-apple/build.gradle
@@ -2,8 +2,8 @@ apply plugin : 'java-library'
 apply plugin : 'robovm'
 apply from : '../publish_java.gradle'
 
-sourceCompatibility = 11
-targetCompatibility = 11
+sourceCompatibility = JavaVersion.VERSION_1_8
+targetCompatibility = JavaVersion.VERSION_1_8
 
 
 dependencies {
diff --git a/gdx-pay-server/build.gradle b/gdx-pay-server/build.gradle
index c873007..c826aa4 100644
--- a/gdx-pay-server/build.gradle
+++ b/gdx-pay-server/build.gradle
@@ -1,8 +1,8 @@
 apply plugin : 'java-library'
 apply from : '../publish_java.gradle'
 
-sourceCompatibility = 11
-targetCompatibility = 11
+sourceCompatibility = JavaVersion.VERSION_1_8
+targetCompatibility = JavaVersion.VERSION_1_8
 
 sourceSets {
     main {
diff --git a/gdx-pay/build.gradle b/gdx-pay/build.gradle
index d77b07c..3218cff 100644
--- a/gdx-pay/build.gradle
+++ b/gdx-pay/build.gradle
@@ -1,7 +1,7 @@
 apply plugin: 'java-library'
 
-sourceCompatibility = 11
-targetCompatibility = 11
+sourceCompatibility = JavaVersion.VERSION_1_8
+targetCompatibility = JavaVersion.VERSION_1_8
 
 apply from : '../publish_java.gradle'