diff --git a/.github/workflows/actions.yml b/.github/workflows/actions.yml
index 07ea252a..162e3833 100644
--- a/.github/workflows/actions.yml
+++ b/.github/workflows/actions.yml
@@ -13,7 +13,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        ruby: [ '2.5', '2.6', '2.7', '3.0', 'truffleruby-head' ]
+        ruby: [ '2.5', '2.6', '2.7', '3.0', '3.1', 'ruby-head', 'truffleruby-head' ]
         os: ['ubuntu-latest', 'macos-latest']
         task: [test]
         include:
diff --git a/kubeclient.gemspec b/kubeclient.gemspec
index 961b4401..ef39da44 100644
--- a/kubeclient.gemspec
+++ b/kubeclient.gemspec
@@ -31,6 +31,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'googleauth', '~> 0.5.1'
   spec.add_development_dependency('mocha', '~> 1.5')
   spec.add_development_dependency 'openid_connect', '~> 1.1'
+  spec.add_development_dependency 'net-smtp'
 
   spec.add_dependency 'jsonpath', '~> 1.0'
   spec.add_dependency 'rest-client', '~> 2.0'