diff --git a/.github/workflows/CI_build.yml b/.github/workflows/CI_build.yml
index b132bfc..3f80c9b 100644
--- a/.github/workflows/CI_build.yml
+++ b/.github/workflows/CI_build.yml
@@ -93,9 +93,8 @@ jobs:
         run: |
           env | sort
       - name: Build documentation
-        shell: bash -l {0}
         run: |
-          make coverage doctest html
+          poetry run make coverage doctest html
         working-directory: readthedocs/
         env:
           SPHINXOPTS: "-n"  # enable nit-picky mode