diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index ef469db..59920b9 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -36,12 +36,8 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        # Due to https://github.com/actions/runner/issues/849, we have to use quotes for '3.0'
-        ruby: [ 3.1, '3.0', 2.7, jruby, truffleruby ]
-        gemfile: [ '7.0', '6.1' ]
-        exclude:
-          - ruby: jruby
-            gemfile: '7.0' # requires ruby 2.7
+        ruby: [ 3.3, 3.2, 3.1, jruby, truffleruby ]
+        gemfile: [ '7.1', '7.0', '6.1' ]
     env:
       BUNDLE_GEMFILE: ${{ github.workspace }}/gemfiles/rails_${{ matrix.gemfile }}.gemfile
     steps:
diff --git a/lib/simple_workflow/middleware.rb b/lib/simple_workflow/middleware.rb
index d4af882..ece041f 100644
--- a/lib/simple_workflow/middleware.rb
+++ b/lib/simple_workflow/middleware.rb
@@ -82,13 +82,13 @@ def remove_discarded_flashes(session)
     Rails.logger.warn "simple_workflow: session: #{session.to_hash}"
   end
 
-  if ActionPack::VERSION::MAJOR >= 5
+  if ActionPack::VERSION::MAJOR >= 7
     def serialize_session(cookie_jar, session)
-      cookie_jar.send(:serialize, session)
+      cookie_jar.send(:serializer).send(:dump, session)
     end
-  else # Rails 4.x
+  else # Rails 6
     def serialize_session(cookie_jar, session)
-      cookie_jar.send(:serialize, nil, session)
+      cookie_jar.send(:serialize, session)
     end
   end
 
diff --git a/lib/simple_workflow/version.rb b/lib/simple_workflow/version.rb
index 1ee64bb..d7164ff 100644
--- a/lib/simple_workflow/version.rb
+++ b/lib/simple_workflow/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module SimpleWorkflow
-  VERSION = '2.2.0'
+  VERSION = '2.2.1'
 end
diff --git a/simple_workflow.gemspec b/simple_workflow.gemspec
index 51692d0..bd4dffe 100644
--- a/simple_workflow.gemspec
+++ b/simple_workflow.gemspec
@@ -11,11 +11,11 @@ Gem::Specification.new do |s|
   s.summary = 'Add simple breadcrumbs "detour" workflow to Ruby On Rails.'
   s.homepage = 'https://github.com/donv/simple_workflow'
   s.description = 'Expands Ruby on Rails to allow simple breadcrumb detour workflows.'
-  s.required_ruby_version = '>= 2.7', '<4'
+  s.required_ruby_version = '~> 3.1'
   s.licenses = %w[MIT]
   s.files = Dir['[A-Z]*', 'lib/**/*', 'test/**/*']
 
-  s.add_runtime_dependency('rails', '>=6.2', '<8')
+  s.add_runtime_dependency('rails', '>=6.1', '<8')
 
   s.add_development_dependency('rubocop', '~>1.0')
   s.add_development_dependency('rubocop-performance', '~>1.5')