diff --git a/.github/workflows/rspec_rubocop.yml b/.github/workflows/rspec_rubocop.yml
index dd987f8..68d562f 100644
--- a/.github/workflows/rspec_rubocop.yml
+++ b/.github/workflows/rspec_rubocop.yml
@@ -15,6 +15,7 @@ defaults:
 jobs:
   test:
     runs-on: ubuntu-latest
+    container: ubuntu:focal
     strategy:
       matrix:
         include: # use bundler 2.3 for ruby versions < 2.6 (https://bundler.io/compatibility.html)
@@ -31,7 +32,7 @@ jobs:
     steps:
     - uses: actions/checkout@v3
     - name: Set up Ruby
-      uses: ruby/setup-ruby@ee2113536afb7f793eed4ce60e8d3b26db912da4 # v1.127.0
+      uses: ruby/setup-ruby@v1.143.0
       with:
         ruby-version: ${{ matrix.ruby-version }}
         bundler: ${{ matrix.bundler-version }}