diff --git a/.github/actions/post-checkout/action.yml b/.github/actions/post-checkout/action.yml
index a43ad01e8..7878e0edb 100644
--- a/.github/actions/post-checkout/action.yml
+++ b/.github/actions/post-checkout/action.yml
@@ -18,6 +18,7 @@ runs:
           fi;
         done << (git diff --name-only "${GITHUB_BASE_SHA}" "${GITHUB_PR_SHA}");
         echo "docs_only=${docs_only}" >> $GITHUB_OUTPUT;
+      shell: bash
 
     - name: Get Composer cache directory
       id: composer-cache