diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 7e6daa3..c3fdf3a 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -3,7 +3,7 @@ on:
   pull_request:
     branches: ["*"]
   push:
-    branches: [master]
+    branches: [main]
 jobs:
   test:
     strategy:
@@ -11,6 +11,8 @@ jobs:
       matrix:
         # https://bundler.io/compatibility.html
         ruby:
+          - version: ruby-4.0
+            bundler: "4.0"
           - version: ruby-3.4
             bundler: "2.6"
           - version: ruby-3.3
@@ -19,9 +21,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - name: Setup Ruby
-        uses: ruby/setup-ruby@v1
+        uses: ruby/setup-ruby@95ef2b042f9d7a56d8268cba8559e2842e2ad01b # v1.321.0
         with:
           ruby-version: ${{ matrix.ruby.version }}
       - name: Install bundler
@@ -34,17 +36,17 @@ jobs:
   publish:
     name: Publish to GitHub Packages
     needs: test
-    if: github.event_name == 'push' && github.ref == 'refs/heads/master'
+    if: github.event_name == 'push' && github.ref == 'refs/heads/main'
     runs-on: ubuntu-latest
     permissions:
       contents: read
       packages: write
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
       - name: Setup Ruby
-        uses: ruby/setup-ruby@v1
+        uses: ruby/setup-ruby@95ef2b042f9d7a56d8268cba8559e2842e2ad01b # v1.321.0
         with:
           ruby-version: ruby-3.4
 
diff --git a/.gitignore b/.gitignore
index 8f3f2ba..93e96cc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@
 *.gem
 /.bundle
 /Gemfile.lock
+.serena/
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8bf1995..d032a09 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.1.0] - 2026-09-09
+
+### Changed
+
+- Add support for Ruby 4.0.x and remove the upper bound on `required_ruby_version`.
+- Relax the `bundler` development dependency to `>= 2.0` so `bundle install` works with Bundler 4 (bundled with Ruby 4.0).
+
 ## [1.0.0] - 2025-03-03
 
 ### Changed
diff --git a/lib/memorb/version.rb b/lib/memorb/version.rb
index 2e00a13..24d5984 100644
--- a/lib/memorb/version.rb
+++ b/lib/memorb/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module Memorb
-  VERSION = '1.0.0'
+  VERSION = '1.1.0'
 end
diff --git a/memorb.gemspec b/memorb.gemspec
index c0b3da9..e048c5d 100644
--- a/memorb.gemspec
+++ b/memorb.gemspec
@@ -21,10 +21,10 @@ Gem::Specification.new do |s|
   s.metadata["homepage_uri"] = s.homepage
   s.metadata["source_code_uri"] = s.homepage
 
-  s.required_ruby_version     = '>= 2.3', '< 3.5'
+  s.required_ruby_version     = '>= 2.3'
   s.required_rubygems_version = '>= 2.5'
 
-  s.add_development_dependency 'bundler', '~> 2.0'
+  s.add_development_dependency 'bundler', '>= 2.0'
   s.add_development_dependency 'rspec', '~> 3.9'
   s.add_dependency 'concurrent-ruby', '~> 1.1'