diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1211f44..2fc9ea9 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -12,13 +12,13 @@ jobs:
   test:
     strategy:
       matrix:
-        java: ['11', '17']
+        java: ['11', '21']
         os: [ubuntu-latest, macos-latest, windows-latest]
         exclude:
           - os: macos-latest
-            java: '17'
+            java: '21'
           - os: windows-latest
-            java: '17'
+            java: '21'
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v3
diff --git a/asciidoctorj-diagram-jsyntrax/gradle.properties b/asciidoctorj-diagram-jsyntrax/gradle.properties
index 4f32ec6..d1fe543 100644
--- a/asciidoctorj-diagram-jsyntrax/gradle.properties
+++ b/asciidoctorj-diagram-jsyntrax/gradle.properties
@@ -1,5 +1,5 @@
 properName=AsciidoctorJ Diagram JSyntrax
 description=AsciidoctorJ Diagram JSyntrax bundles the Asciidoctor Diagram JSyntrax RubyGem (asciidoctor-diagram-jsyntrax) so it can be loaded into the JVM using JRuby.
-version=1.38.1
+version=1.38.2
 gem_name=asciidoctor-diagram-jsyntrax
 
diff --git a/build.gradle b/build.gradle
index 264ef3c..fc79859 100644
--- a/build.gradle
+++ b/build.gradle
@@ -12,13 +12,19 @@ buildscript {
     mavenCentral()
     maven { url "https://oss.sonatype.org/content/repositories/snapshots/" }
   }
+  dependencies {
+    classpath("com.github.jruby-gradle:jruby-gradle-plugin:2.0.1") {
+      exclude module: 'grolifant'
+      exclude module: 'okhttp-digest'
+    }
+    classpath 'org.ysb33r.gradle:grolifant:0.17.0'
+  }
 }
 
 // modern plugins config
 plugins {
   id "signing"
   id "io.github.gradle-nexus.publish-plugin" version "1.1.0"
-  id 'com.github.jruby-gradle.base' version '2.0.0'
 }
 
 // TIP use -PpublishRelease=true to active release behavior regardless of the version