diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 575e24d..cd6a76d 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java: [ 8, 11, 17 ]
+        java: [ 8, 11, 17, 21 ]
     name: Java ${{ matrix.java }}
     steps:
       - uses: actions/checkout@v3
diff --git a/pom.xml b/pom.xml
index f3ae197..e602745 100644
--- a/pom.xml
+++ b/pom.xml
@@ -283,7 +283,7 @@ limitations under the License.
         <profile>
             <id>proguard</id>
             <activation>
-                <jdk>[9,)</jdk>
+                <jdk>[9,19]</jdk>
             </activation>
             <build>
                 <plugins>