diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index 6e83cc398..82dfed58e 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -54,6 +54,28 @@ jobs:
       run: |
         find .m2/repository -name "*SNAPSHOT*" -type d | xargs rm -rf {}
 
+  openjdk21:
+    runs-on: [ubuntu-20.04]
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up JDK 21
+      uses: actions/setup-java@v3
+      with:
+        java-version: 21
+        distribution: 'temurin'
+    - name: Maven repository caching
+      uses: actions/cache@v3
+      with:
+        path: ~/.m2/repository
+        key: gwc-${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}
+        restore-keys: |
+          ${{ runner.os }}-maven-
+    - name: Build with Maven
+      run: mvn -B clean install -Dspotless.apply.skip=true -Dall -T2 --file geowebcache/pom.xml
+    - name: Remove SNAPSHOT jars from repository
+      run: |
+        find .m2/repository -name "*SNAPSHOT*" -type d | xargs rm -rf {}
+
   QA:
     runs-on: [ubuntu-20.04]
     steps:
diff --git a/geowebcache/pom.xml b/geowebcache/pom.xml
index 0208659a7..d2a6e8108 100644
--- a/geowebcache/pom.xml
+++ b/geowebcache/pom.xml
@@ -94,7 +94,7 @@
     <lint>deprecation,unchecked</lint>
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
     <jclouds.version>2.3.0</jclouds.version>
-    <mockito.version>3.12.4</mockito.version>
+    <mockito.version>5.6.0</mockito.version>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
   </properties>
 
@@ -290,7 +290,7 @@
       <dependency>
         <groupId>org.easymock</groupId>
         <artifactId>easymock</artifactId>
-        <version>5.0.1</version>
+        <version>5.2.0</version>
         <scope>test</scope>
       </dependency>
       <dependency>