diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index de6f26f..0b72d60 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -31,7 +31,7 @@ jobs:
       - run: bundle exec rake
 
   cruby-nokogiri-system-libraries:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2
       - uses: ruby/setup-ruby@v1