diff --git a/EpcQrCodeRest/build.gradle b/EpcQrCodeRest/build.gradle
index 04b5358..5c3c9be 100644
--- a/EpcQrCodeRest/build.gradle
+++ b/EpcQrCodeRest/build.gradle
@@ -1,6 +1,6 @@
 plugins {
     id 'org.jetbrains.kotlin.jvm'
-    id "org.jetbrains.kotlin.plugin.allopen" version "1.4.10"
+    id "org.jetbrains.kotlin.plugin.allopen" version "1.6.10"
     id 'io.quarkus'
 }
 
@@ -8,18 +8,20 @@ group 'net.dankito.banking.epcqrcode'
 version '1.0.0-SNAPSHOT'
 
 
+def javaVersion = JavaVersion.VERSION_11
+
 java {
-    sourceCompatibility = JavaVersion.VERSION_11
-    targetCompatibility = JavaVersion.VERSION_11
+    sourceCompatibility = javaVersion
+    targetCompatibility = javaVersion
 }
 
 compileKotlin {
-    kotlinOptions.jvmTarget = JavaVersion.VERSION_11
+    kotlinOptions.jvmTarget = javaVersion
     kotlinOptions.javaParameters = true
 }
 
 compileTestKotlin {
-    kotlinOptions.jvmTarget = JavaVersion.VERSION_11
+    kotlinOptions.jvmTarget = javaVersion
 }