diff --git a/.circleci/config.yml b/.circleci/config.yml
index 8666cc0b..65370fee 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -2,7 +2,7 @@ version: 2.1
 executors:
   docker-executor:
     docker:
-      - image: circleci/openjdk:17-buster-node-browsers-legacy
+      - image: circleci/openjdk:13.0-buster-node-browsers-legacy
 
 jobs:
   build_and_push_tag_image:
diff --git a/build.gradle b/build.gradle
index 817be26e..e5ecb6a7 100644
--- a/build.gradle
+++ b/build.gradle
@@ -33,7 +33,7 @@ dependencies {
 
 group = 'hu.dpc.phee'
 version = '1.0.0-SNAPSHOT'
-sourceCompatibility = '1.8'
+sourceCompatibility = '11'
 
 publishing {
     publications {