diff --git a/.github/workflows/key4hep.yml b/.github/workflows/key4hep.yml
index f831301fe..ea1cc53c7 100644
--- a/.github/workflows/key4hep.yml
+++ b/.github/workflows/key4hep.yml
@@ -13,8 +13,8 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        release: ["sw.hsf.org/key4hep",
-                  "sw-nightlies.hsf.org/key4hep"]
+        include:
+          - release: "sw-nightlies.hsf.org/key4hep"
     steps:
     - uses: actions/checkout@v3
     - uses: cvmfs-contrib/github-action-cvmfs@v3
@@ -30,7 +30,8 @@ jobs:
             -DCMAKE_INSTALL_PREFIX=../install \
             -DCMAKE_CXX_STANDARD=17 \
             -DCMAKE_CXX_FLAGS=" -fdiagnostics-color=always -Werror -Wno-error=deprecated-declarations " \
-            -DUSE_EXTERNAL_CATCH2=ON \
+            -DUSE_EXTERNAL_CATCH2=AUTO \
+            -DUSE_EXTERNAL_CATCH2=AUTO \
             -G Ninja ..
           echo "::endgroup::"
           echo "::group::Build"
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index a57fa321a..dc13d8a7d 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -13,12 +13,16 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        sio: [ON]
-        LCG: ["LCG_102/x86_64-centos7-clang12-opt",
-              "LCG_102/x86_64-centos8-gcc11-opt",
-              "dev3/x86_64-centos7-clang12-opt",
-              "dev4/x86_64-centos7-gcc11-opt",
-              "dev4/x86_64-centos7-clang12-opt"]
+        LCG: ["dev3/x86_64-el9-clang16-opt",
+              "dev4/x86_64-el9-clang16-opt"]
+        CXX_STANDARD: [20]
+        include:
+          - LCG: "dev4/x86_64-centos7-gcc11-opt"
+            CXX_STANDARD: 17
+          - LCG: "LCG_102/x86_64-centos7-clang12-opt"
+            CXX_STANDARD: 17
+          - LCG: "LCG_102/x86_64-centos8-gcc11-opt"
+            CXX_STANDARD: 17
     steps:
     - uses: actions/checkout@v3
     - uses: cvmfs-contrib/github-action-cvmfs@v3
@@ -29,9 +33,9 @@ jobs:
           echo "::group::Run CMake"
           mkdir build install
           cd build
-          cmake -DENABLE_SIO=${{ matrix.sio }} \
+          cmake -DENABLE_SIO=ON \
             -DCMAKE_INSTALL_PREFIX=../install \
-            -DCMAKE_CXX_STANDARD=17 \
+            -DCMAKE_CXX_STANDARD=${{ matrix.CXX_STANDARD }} \
             -DCMAKE_CXX_FLAGS=" -fdiagnostics-color=always -Werror -Wno-error=deprecated-declarations " \
             -DUSE_EXTERNAL_CATCH2=OFF \
             -G Ninja ..