diff --git a/.github/workflows/html5validator.yml b/.github/workflows/html5validator.yml
index 1e617b3..5f8d464 100644
--- a/.github/workflows/html5validator.yml
+++ b/.github/workflows/html5validator.yml
@@ -11,7 +11,7 @@ jobs:
 
       - uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 3.1
+          ruby-version: ".ruby-version"
           bundler-cache: true # runs 'bundle install' and caches installed gems automatically
 
       - name: Jekyll build
diff --git a/.ruby-version b/.ruby-version
new file mode 100644
index 0000000..eb39e53
--- /dev/null
+++ b/.ruby-version
@@ -0,0 +1 @@
+3.3