diff --git a/.github/workflows/unit-tests.yml b/.github/workflows/unit-tests.yml
index 8e0af4e78..087a23c63 100644
--- a/.github/workflows/unit-tests.yml
+++ b/.github/workflows/unit-tests.yml
@@ -23,6 +23,7 @@ jobs:
         include:
           - { jdkVersion: "1.11.0", jvmName: "temurin:1.11.0", extraOpts: '-J-XX:+UnlockExperimentalVMOptions -J-XX:+UseJVMCICompiler' }
           - { jdkVersion: "1.17.0", jvmName: "temurin:1.17.0", extraOpts: '' }
+          - { jdkVersion: "1.21.0", jvmName: "temurin:1.21", extraOpts: '' }
     steps:
       - name: Checkout
         uses: actions/checkout@v3.1.0
@@ -39,9 +40,11 @@ jobs:
         uses: coursier/cache-action@v6.4.0
 
       - name: Set up JDK ${{ matrix.jdkVersion }}
-        uses: coursier/setup-action@v1.3.0
+        uses: coursier/setup-action@v1.3.4
         with:
           jvm: ${{ matrix.jvmName }}
+          # FIXME default index not giving us access to JDK 21 (yet)
+          jvm-index: https://raw.githubusercontent.com/coursier/jvm-index/32d659500e6c65efb9eee91718a0fb0e797ad4ee/index.json
 
       # hack to solve "Cannot assign requested address" issue - https://github.community/t/github-action-and-oserror-errno-99-cannot-assign-requested-address/173973/1
       - name: Add the current IP address, long hostname and short hostname record to /etc/hosts file