diff --git a/.github/workflows/build-test.yml b/.github/workflows/build-test.yml
index 54c396fce6..1232773e3a 100644
--- a/.github/workflows/build-test.yml
+++ b/.github/workflows/build-test.yml
@@ -36,6 +36,8 @@ jobs:
             runner: [ ubuntu-24.04-ppc64le ]
           - env: { COMPILER: "gcc",   COMPILER_VERSION: "13", LINKER: "mold"  }
             runner: [ ubuntu-24.04-arm ]
+          - env: { COMPILER: "clang", COMPILER_VERSION: "18", LINKER: "lld"  }
+            runner: [ ubuntu-24.04-s390x ]
     env: ${{ matrix.env }}
     steps:
       - name: Repository checkout
diff --git a/.github/workflows/unit-tests.yml b/.github/workflows/unit-tests.yml
index e92430274e..4e4c9c964c 100644
--- a/.github/workflows/unit-tests.yml
+++ b/.github/workflows/unit-tests.yml
@@ -29,11 +29,15 @@ jobs:
             runner: ubuntu-24.04-arm
           - run_phase: GCC
             runner: ubuntu-24.04-ppc64le
+          - run_phase: GCC
+            runner: ubuntu-24.04-s390x
           - run_phase: CLANG
           - run_phase: CLANG
             runner: ubuntu-24.04-arm
           - run_phase: CLANG
             runner: ubuntu-24.04-ppc64le
+          - run_phase: CLANG
+            runner: ubuntu-24.04-s390x
     steps:
       - name: Repository checkout
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683