diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 6c2a5d94a..bee8a6d52 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -23,7 +23,9 @@ jobs:
            timeout: 5
          - ruby: '3.0'
            timeout: 5
-         - ruby: truffleruby
+         - ruby: 3.1
+           timeout: 5
+         - ruby: truffleruby-head
            timeout: 50
          - ruby: jruby
            timeout: 5
@@ -32,10 +34,11 @@ jobs:
     - uses: ruby/setup-ruby@v1
       with:
         ruby-version: ${{ matrix.ruby }}
+        rubygems: 3.3.12
         bundler-cache: true
     - name: Run tests
       run: bundle exec rake spec
-      continue-on-error: ${{ matrix.ruby == 'truffleruby' }}
+      continue-on-error: ${{ matrix.ruby == 'truffleruby-head' }}
   actionmailer:
     runs-on: ubuntu-latest
     steps:
diff --git a/Gemfile b/Gemfile
index 36f85c60c..d153d8fc8 100644
--- a/Gemfile
+++ b/Gemfile
@@ -13,3 +13,5 @@ gem 'jruby-openssl', :platforms => :jruby
 gem 'mini_mime'
 
 gem 'byebug', :platforms => :mri
+
+gem "strscan", ">= 3.0.2.pre1"
diff --git a/mail.gemspec b/mail.gemspec
index e36dddc41..5813e2db5 100644
--- a/mail.gemspec
+++ b/mail.gemspec
@@ -16,6 +16,9 @@ Gem::Specification.new do |s|
   s.required_ruby_version = ">= 2.5"
 
   s.add_dependency('mini_mime', '>= 0.1.1')
+  s.add_dependency('net-smtp')
+  s.add_dependency('net-imap')
+  s.add_dependency('net-pop')
 
   s.add_development_dependency('bundler', '>= 1.0.3')
   s.add_development_dependency('rake', '> 0.8.7')