diff --git a/docs/getting-started-kotlin/build.gradle.kts b/docs/getting-started-kotlin/build.gradle.kts
index 6810b29539..1bc59a683f 100644
--- a/docs/getting-started-kotlin/build.gradle.kts
+++ b/docs/getting-started-kotlin/build.gradle.kts
@@ -25,6 +25,11 @@ tasks.withType<KotlinCompile> {
     kotlinOptions.jvmTarget = "1.8"
 }
 
+java {
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
+}
+
 application {
     mainClass.set("MainKt")
 }