diff --git a/.github/workflows/main.yaml b/.github/workflows/main.yaml
index 972f1b898..6c98a60d2 100644
--- a/.github/workflows/main.yaml
+++ b/.github/workflows/main.yaml
@@ -70,8 +70,12 @@ jobs:
           os: ubuntu-24.04
         - target: powerpc64le-unknown-linux-gnu
           os: ubuntu-24.04
+        - target: powerpc64le-unknown-linux-gnu
+          os: ubuntu-24.04-ppc64le
         - target: riscv64gc-unknown-linux-gnu
           os: ubuntu-24.04
+        - target: s390x-unknown-linux-gnu
+          os: ubuntu-24.04-s390x
         - target: thumbv6m-none-eabi
           os: ubuntu-24.04
         - target: thumbv7em-none-eabi
@@ -105,8 +109,21 @@ jobs:
       TEST_VERBATIM: ${{ matrix.test_verbatim }}
       MAY_SKIP_LIBM_CI: ${{ needs.calculate_vars.outputs.may_skip_libm_ci }}
     steps:
+    - name: Print $HOME
+      shell: bash
+      run: |
+        set -x
+        echo "${HOME:-not found}"
+        pwd
+        printenv
     - name: Print runner information
       run: uname -a
+
+    # Native ppc and s390x runners don't have rustup by default
+    - name: Install rustup
+      if: matrix.os == 'ubuntu-24.04-ppc64le' || matrix.os == 'ubuntu-24.04-s390x'
+      run: sudo apt-get update && sudo apt-get install -y rustup
+
     - uses: actions/checkout@v4
     - name: Install Rust (rustup)
       shell: bash
@@ -117,7 +134,12 @@ jobs:
         rustup update "$channel" --no-self-update
         rustup default "$channel"
         rustup target add "${{ matrix.target }}"
+
+    # Our scripts use nextest if possible. This is skipped on the native ppc
+    # and s390x runners since install-action doesn't support them.
     - uses: taiki-e/install-action@nextest
+      if: "!(matrix.os == 'ubuntu-24.04-ppc64le' || matrix.os == 'ubuntu-24.04-s390x')"
+
     - uses: Swatinem/rust-cache@v2
       with:
         key: ${{ matrix.target }}