diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index b48ee73..bf54332 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -23,6 +23,7 @@ jobs:
       - name: Set up Ruby
         uses: ruby/setup-ruby@ece82769428359c077b5a5eaff268902a303c101
         with:
+          ruby-version: "2.4.19"
           bundler-cache: true # runs 'bundle install' and caches installed gems automatically
       - run: ./scripts/build-data.sh --remote
       - name: Set up Pages