diff --git a/.github/workflows/unit_tests_with_nightly_puppet_gem.yaml b/.github/workflows/unit_tests_with_nightly_puppet_gem.yaml
index 3771305..27f9012 100644
--- a/.github/workflows/unit_tests_with_nightly_puppet_gem.yaml
+++ b/.github/workflows/unit_tests_with_nightly_puppet_gem.yaml
@@ -51,7 +51,9 @@ jobs:
         run: |
           ${{ matrix.extra_steps }}
           curl https://artifactory.delivery.puppetlabs.net/artifactory/internal_nightly__local/downloads/gems/puppet${{ matrix.puppet_version }}-nightly/${{ matrix.gem_file }} --output puppet.gem --location
-          gem install puppet.gem -N --source https://artifactory.delivery.puppetlabs.net/artifactory/api/gems/rubygems/
+          gem sources --add https://artifactory.delivery.puppetlabs.net/artifactory/api/gems/rubygems/
+          gem sources --remove https://rubygems.org/
+          gem install puppet.gem -N
 
       - name: Prepare testing environment with bundler
         env: