diff --git a/.github/workflows/publish_pypi.yml b/.github/workflows/publish_pypi.yml
index 57d7dca..2f5c1ab 100644
--- a/.github/workflows/publish_pypi.yml
+++ b/.github/workflows/publish_pypi.yml
@@ -46,7 +46,8 @@ jobs:
           if ! command -v clang-24 >/dev/null 2>&1; then
             echo "deb [trusted=yes] https://apt.llvm.org/noble/ llvm-toolchain-noble main" | sudo tee /etc/apt/sources.list.d/llvm-toolchain-noble.list
             sudo apt update
-            sudo apt install -y clang-24 lld-24 libclang-24-dev
+            # libeigen3-dev: Eigen 3.4.0 for libczirw (see the cmake-shim step below)
+            sudo apt install -y clang-24 lld-24 libclang-24-dev libeigen3-dev
           fi
         shell: bash
 
@@ -95,6 +96,40 @@ jobs:
             mv ~/osxcross ~/.osxcross
           fi
 
+      - name: Prefer system Eigen in the libczirw cmake build
+        run: |
+          # libczirw-sys cmake build clones Eigen3 from gitlab.com (ExternalProject);
+          # that clone is flaky on this runner (it is the only git-based network step
+          # left in the build). noble libeigen3-dev is the same Eigen 3.4.0 that libczi
+          # pins, and libczi has an upstream option to use it - flip that option for
+          # the libCZI project via CMAKE_PROJECT_INCLUDE. cmake does not read that
+          # variable from the environment, so a cmake shim injects it (-D); the shim is
+          # scoped to invocations that look like the libczi configure (no-op for
+          # --build / --version / other uses).
+          mkdir -p /root/ci-shims
+          cat > /root/cm-override-libczi.cmake <<'CMAKEEOF'
+          if (CMAKE_PROJECT_NAME STREQUAL "libCZI")
+            set(LIBCZI_BUILD_PREFER_EXTERNALPACKAGE_EIGEN3 ON CACHE BOOL "" FORCE)
+          endif()
+          CMAKEEOF
+          cat > /root/ci-shims/cmake <<'SHIMEOF'
+          #!/usr/bin/env bash
+          case "$*" in
+            --build*)
+              exec /usr/bin/cmake "$@" ;;
+            *libczi*)
+              exec /usr/bin/cmake -DCMAKE_PROJECT_INCLUDE=/root/cm-override-libczi.cmake "$@" ;;
+            *)
+              exec /usr/bin/cmake "$@" ;;
+          esac
+          SHIMEOF
+          chmod +x /root/ci-shims/cmake
+          echo "--- /root/cm-override-libczi.cmake ---"
+          cat /root/cm-override-libczi.cmake
+          echo "--- /root/ci-shims/cmake ---"
+          cat /root/ci-shims/cmake
+        shell: bash
+
       - name: Build wheels
         env:
           # ziglang >= 0.17's bundled libc++ needs these -D_LIBCPP_* macros when
@@ -110,6 +145,9 @@ jobs:
         shell: bash
         run: |
           export PATH="$HOME/.osxcross/bin:$PATH"
+          # put the cmake shim (system-Eigen override for libczirw) in front
+          export PATH="/root/ci-shims:$PATH"
+          command -v cmake
           echo "HOME=$HOME CARGO_HOME=$CARGO_HOME RUSTUP_HOME=$RUSTUP_HOME"
           command -v cargo-zigbuild || echo "cargo-zigbuild: not on PATH"
           cargo-zigbuild --version 2>&1 || true