diff --git a/.github/workflows/ruby.yml b/.github/workflows/ruby.yml
index 6d45e4e..b2f754c 100644
--- a/.github/workflows/ruby.yml
+++ b/.github/workflows/ruby.yml
@@ -28,30 +28,23 @@ jobs:
         # | 7.0   |   4/2025  |   2.7   | 3.3     |
         # | 7.1   |  10/2025  |   2.7   |         |
         # | 7.2   |   8/2026  |   3.1   |         |
-        # | 8.0   | ~11/2026  |   3.2   |         |
-        ruby: ['3.0', '3.1', '3.2', '3.3', '3.4']
-        gemfile:
-          - 'gemfiles/rails_6.1.gemfile'
-          - 'gemfiles/rails_7.0.gemfile'
-          - 'gemfiles/rails_7.1.gemfile'
-          - 'gemfiles/rails_7.2.gemfile'
-          - 'gemfiles/rails_8.0.gemfile'
-        exclude:
-        - ruby: '3.0'
-          gemfile: 'gemfiles/rails_7.2.gemfile'
-        - ruby: '3.0'
-          gemfile: 'gemfiles/rails_8.0.gemfile'
-        - ruby: '3.1'
-          gemfile: 'gemfiles/rails_8.0.gemfile'
-        - ruby: '3.4'
-          gemfile: 'gemfiles/rails_6.1.gemfile'
-        - ruby: '3.4'
-          gemfile: 'gemfiles/rails_7.0.gemfile'
+        # | 8.0   |  11/2026  |   3.2   |         |
+        # | 8.1   |  10/2027  |   3.2   |         |
+        include:
+          - { ruby: '3.0', gemfile: 'gemfiles/rails_6.1.gemfile' }
+          - { ruby: '3.1', gemfile: 'gemfiles/rails_7.0.gemfile' }
+          - { ruby: '3.2', gemfile: 'gemfiles/rails_7.1.gemfile' }
+          - { ruby: '3.2', gemfile: 'gemfiles/rails_7.2.gemfile' }
+          # Active Rails
+          - { ruby: '3.3', gemfile: 'gemfiles/rails_8.0.gemfile' }
+          - { ruby: '3.4', gemfile: 'gemfiles/rails_8.0.gemfile' }
+          - { ruby: '3.4', gemfile: 'gemfiles/rails_8.1.gemfile' }
+          - { ruby: '4.0', gemfile: 'gemfiles/rails_8.1.gemfile' }
     env:
       BUNDLE_GEMFILE: ${{ matrix.gemfile }}
     name: Ruby ${{ matrix.ruby }}, ${{ matrix.gemfile }}
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - name: Set up Ruby
       uses: ruby/setup-ruby@v1
       with:
diff --git a/README.md b/README.md
index 148b671..07fc206 100644
--- a/README.md
+++ b/README.md
@@ -38,7 +38,7 @@ Requirements:
 
 - v1.x: Ruby >= 1.9.3, Rails >= 2.2.2
 - v2.x, v3.x: Ruby >= 2.4, Rails >= 5
-- upcoming: Ruby >= 3.0, Rails >= 6.1
+- v4.x: Ruby >= 3.0, Rails >= 6.1
 
 ```ruby
 gem 'active_hash', '~> 1.5.3'
diff --git a/gemfiles/rails_8.1.gemfile b/gemfiles/rails_8.1.gemfile
new file mode 100644
index 0000000..673479d
--- /dev/null
+++ b/gemfiles/rails_8.1.gemfile
@@ -0,0 +1,17 @@
+source 'http://rubygems.org/'
+
+gem 'activerecord', '~> 8.1.0'
+gem 'rspec', '~> 3.13'
+gem 'rake', '~> 13.2'
+gem 'json'
+gem 'test-unit'
+
+platform :jruby do
+  gem 'activerecord-jdbcsqlite3-adapter', '>= 1.3.6'
+end
+
+platform :ruby do
+  gem 'sqlite3'
+end
+
+gemspec :path => '../'