diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0b4968cc8..279a1e7a0 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -102,6 +102,7 @@ jobs:
         -DPYBIND11_WERROR=ON
         -DDOWNLOAD_CATCH=ON
         -DDOWNLOAD_EIGEN=ON
+        -DPYBIND11_EIGEN_REPO=https://gitlab.com/libeigen/eigen-backup
         -DCMAKE_CXX_STANDARD=11
         ${{ matrix.args }}
 
@@ -129,6 +130,7 @@ jobs:
         -DPYBIND11_WERROR=ON
         -DDOWNLOAD_CATCH=ON
         -DDOWNLOAD_EIGEN=ON
+        -DPYBIND11_EIGEN_REPO=https://gitlab.com/libeigen/eigen-backup
         -DCMAKE_CXX_STANDARD=17
         ${{ matrix.args }}
         ${{ matrix.args2 }}
@@ -151,6 +153,7 @@ jobs:
         -DPYBIND11_WERROR=ON
         -DDOWNLOAD_CATCH=ON
         -DDOWNLOAD_EIGEN=ON
+        -DPYBIND11_EIGEN_REPO=https://gitlab.com/libeigen/eigen-backup
         -DCMAKE_CXX_STANDARD=17
         -DPYBIND11_INTERNALS_VERSION=10000000
         "-DPYBIND11_TEST_OVERRIDE=test_call_policies.cpp;test_gil_scoped.cpp;test_thread.cpp"
@@ -249,6 +252,7 @@ jobs:
         -DPYBIND11_WERROR=ON
         -DDOWNLOAD_CATCH=ON
         -DDOWNLOAD_EIGEN=ON
+        -DPYBIND11_EIGEN_REPO=https://gitlab.com/libeigen/eigen-backup
         -DCMAKE_CXX_STANDARD=17
 
     - name: Build
@@ -628,6 +632,7 @@ jobs:
         -DPYBIND11_WERROR=ON
         -DDOWNLOAD_CATCH=ON
         -DDOWNLOAD_EIGEN=ON
+        -DPYBIND11_EIGEN_REPO=https://gitlab.com/libeigen/eigen-backup
         -DCMAKE_CXX_STANDARD=11
         -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
 
@@ -774,6 +779,7 @@ jobs:
         -DPYBIND11_WERROR=ON
         -DDOWNLOAD_CATCH=ON
         -DDOWNLOAD_EIGEN=ON
+        -DPYBIND11_EIGEN_REPO=https://gitlab.com/libeigen/eigen-backup
         ${{ matrix.args }}
     - name: Build C++11
       run: cmake --build build -j 2
@@ -820,6 +826,7 @@ jobs:
         -DPYBIND11_WERROR=ON
         -DDOWNLOAD_CATCH=ON
         -DDOWNLOAD_EIGEN=ON
+        -DPYBIND11_EIGEN_REPO=https://gitlab.com/libeigen/eigen-backup
 
     - name: Build C++14
       run: cmake --build build -j 2
@@ -869,6 +876,7 @@ jobs:
         -DPYBIND11_WERROR=ON
         -DDOWNLOAD_CATCH=ON
         -DDOWNLOAD_EIGEN=ON
+        -DPYBIND11_EIGEN_REPO=https://gitlab.com/libeigen/eigen-backup
         -DCMAKE_CXX_STANDARD=${{ matrix.std }}
         ${{ matrix.args }}
 
diff --git a/.github/workflows/format.yml b/.github/workflows/format.yml
index ab7b40503..7869912bf 100644
--- a/.github/workflows/format.yml
+++ b/.github/workflows/format.yml
@@ -41,6 +41,7 @@ jobs:
         cmake -S . -B build
         -DCMAKE_CXX_CLANG_TIDY="$(which clang-tidy)"
         -DDOWNLOAD_EIGEN=ON
+        -DPYBIND11_EIGEN_REPO=https://gitlab.com/libeigen/eigen-backup
         -DDOWNLOAD_CATCH=ON
         -DCMAKE_CXX_STANDARD=17