diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index b3caebc..c041ea4 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -11,16 +11,12 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v6
-      - uses: coursier/setup-action@v3
+      - name: Restore caches
+        uses: coursier/cache-action@v8
+      - name: Setup Scala
+        uses: coursier/setup-action@v3
         with:
-          jvm: 11
+          jvm: 21
           apps: sbt
-      - name: Cache
-        uses: actions/cache@v5
-        with:
-          path: |
-            ~/.cache/coursier
-            ~/.sbt
-          key: sbt-${{ hashFiles('**/build.sbt', '**/build.properties') }}
       - name: Run tests
         run: sbt +compile +test scalastyle
diff --git a/README.md b/README.md
index 9d7ccfa..490ad59 100644
--- a/README.md
+++ b/README.md
@@ -79,7 +79,7 @@ The NCC Group has conducted an audit of this library - we have a blog post about
 
 ## Building
 
-Recrypt requires openjdk8+ and is known to build under Linux and MacOSX.
+Recrypt requires openjdk21+ and is known to build under Linux and MacOSX.
 
 https://github.com/paulp/sbt-extras can be used to get sbt.
 
diff --git a/flake.nix b/flake.nix
index 845f112..5f44354 100644
--- a/flake.nix
+++ b/flake.nix
@@ -30,4 +30,3 @@
       }
     );
 }
-