diff --git a/.github/workflows/build_wheels.yml b/.github/workflows/build_wheels.yml
index 8123806c..05b2852a 100644
--- a/.github/workflows/build_wheels.yml
+++ b/.github/workflows/build_wheels.yml
@@ -128,7 +128,7 @@ jobs:
       - uses: actions/checkout@v4
       - name: Install cibuildwheel
         # Nb. keep cibuildwheel version pin consistent with job below
-        run: pipx install cibuildwheel==2.20.0
+        run: pipx install cibuildwheel==2.21.1
       - id: set-matrix
         run: |
           echo "CI_ONLY" $CI_ONLY
@@ -180,7 +180,7 @@ jobs:
         with:
           platforms: all          
       - name: Build and test wheels
-        uses: pypa/cibuildwheel@v2.20.0
+        uses: pypa/cibuildwheel@v2.21.1
         env:
           # FIXME: only run the slow tests when doing regular pushes, or manual - not for PRs
           CIBW_TEST_COMMAND: "pytest -v {package}/tests ${{ (github.event_name == 'push' || github.event_name == 'workflow_dispatch') && '--runslow' || '' }}"