diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7b08ad0..648b5c1 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -61,7 +61,8 @@ jobs:
       matrix:
         python:
           # - "3.8" # oldest Python supported by PSF
-          - "3.11" # newest Python that is stable
+          - "3.10" # Required by rhysd/action-setup-vim@v1 on ubuntu-latest
+          # - "3.11" # newest Python that is stable
         platform:
           - ubuntu-latest
         # - macos-latest
@@ -71,7 +72,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: nikeee/setup-pandoc@v1
         with:
-          pandoc-version: '3.1.3' # The pandoc version to download (if necessary) and use.
+          pandoc-version: '3.1.3' # Compatible with tests for reference_citation.py
       - uses: actions/setup-python@v5
         id: setup-python
         with: