diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 307ae721..b0b8fdee 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -19,9 +19,12 @@ jobs:
       matrix:
         ruby_version:
           - "3.2"
+          - "4.0"
         include:
           - ruby_version: '3.2'
             puppet_gem_version: '~> 8.0'
+          - ruby_version: '4.0'
+            puppet_gem_version: '~> 9.0'
         runs_on:
           - "ubuntu-latest"
           - "windows-latest"
diff --git a/.github/workflows/nightly.yml b/.github/workflows/nightly.yml
index fb1e4e50..900c9623 100644
--- a/.github/workflows/nightly.yml
+++ b/.github/workflows/nightly.yml
@@ -12,9 +12,12 @@ jobs:
       matrix:
         ruby_version:
           - "3.2"
+          - "4.0"
         include:
           - ruby_version: '3.2'
             puppet_gem_version: '~> 8.0'
+          - ruby_version: '4.0'
+            puppet_gem_version: '~> 9.0'
         runs_on:
           - "ubuntu-latest"
           - "windows-latest"
diff --git a/Gemfile b/Gemfile
index 6252a780..4fb450c3 100644
--- a/Gemfile
+++ b/Gemfile
@@ -25,7 +25,10 @@ end
 
 group :test do
   gem 'facter', *location_for(ENV.fetch('FACTER_GEM_VERSION', nil))
-  gem 'puppet', *location_for(ENV.fetch('PUPPET_GEM_VERSION', nil))
+
+  source 'https://rubygems-puppetcore.puppet.com' do
+    gem 'puppet', *location_for(ENV.fetch('PUPPET_GEM_VERSION', nil))
+  end
 
   gem 'json_pure'
   gem 'sync'