diff --git a/.github/workflows/python-publish.yml b/.github/workflows/python-publish.yml
index a55a739..70615ba 100644
--- a/.github/workflows/python-publish.yml
+++ b/.github/workflows/python-publish.yml
@@ -32,6 +32,7 @@ jobs:
         build
         --user
     - name: Build a binary wheel and a source tarball
+      shell: bash -l {0}
       run: |
         source /home/firedrake/firedrake/bin/activate
         python3 -m build