diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 31deb3c..b7c0422 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java: [ '11', '15', '17' ]
+        java: [ '11', '15', '17', '21' ]
     name: Java ${{ matrix.Java }}
 
     steps: