diff --git a/.github/workflows/nightly.yml b/.github/workflows/nightly.yml
index c92fffdf..5fa85424 100644
--- a/.github/workflows/nightly.yml
+++ b/.github/workflows/nightly.yml
@@ -21,6 +21,7 @@ jobs:
           # { scalaVersion: "2.13", jdkVersion: "1.11.0", jvmName: "temurin:1.11.0", extraOpts: '-J-XX:+UnlockExperimentalVMOptions -J-XX:+UseJVMCICompiler', testCmd: "test"}
           - { scalaVersion: "2.13", jdkVersion: "1.17.0", jvmName: "temurin:1.17.0", extraOpts: '', testCmd: "test"}
           - { scalaVersion: "3.3",  jdkVersion: "1.17.0", jvmName: "temurin:1.17.0", extraOpts: '', testCmd: "core/test"}
+          - { scalaVersion: "2.13", jdkVersion: "1.21.0", jvmName: "temurin:1.21", extraOpts: '' }
     steps:
       - name: Checkout
         uses: actions/checkout@v3.1.0
@@ -31,9 +32,11 @@ 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
 
       - name: Start DB
         run: |-