diff --git a/.github/workflows/danger.yml b/.github/workflows/danger.yml
index c2db24e..bd89a88 100644
--- a/.github/workflows/danger.yml
+++ b/.github/workflows/danger.yml
@@ -1,17 +1,13 @@
 name: Danger
-on: [pull_request]
+
+on:
+  pull_request:
+    types: [opened, reopened, edited, synchronize]
+
 jobs:
   danger:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v3
-        with:
-          fetch-depth: 0
-      - uses: ruby/setup-ruby@v1
-        with:
-          ruby-version: 2.7
-          bundler-cache: true
-      - run: |
-          # Personal access token for dangerpr-bot - public, but base64 encoded to avoid tripping up GitHub
-          TOKEN=$(echo -n Z2hwX0xNQ3VmanBFeTBvYkZVTWh6NVNqVFFBOEUxU25abzBqRUVuaAo= | base64 --decode)
-          DANGER_GITHUB_API_TOKEN=$TOKEN bundle exec danger --verbose
+    uses: numbata/danger-pr-comment/.github/workflows/danger-run.yml@v0.1.0
+    secrets: inherit
+    with:
+      ruby-version: '3.4'
+      bundler-cache: true
diff --git a/.github/workflows/rubocop.yml b/.github/workflows/rubocop.yml
index 9c3ec95..f0517c7 100644
--- a/.github/workflows/rubocop.yml
+++ b/.github/workflows/rubocop.yml
@@ -8,6 +8,6 @@ jobs:
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 2.7
+          ruby-version: '3.4'
           bundler-cache: true
       - run: bundle exec rubocop
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 838aecb..44be35e 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -9,24 +9,20 @@ jobs:
       fail-fast: false
       matrix:
         entry:
-          - { ruby: '2.6.6', mongo: 'mongo:4.4', mongoid: '5' }
+          - { ruby: '3.1.7', mongo: 'mongo:4.4', mongoid: '5' }
 #          - { ruby: 'jruby-9.1.17.0', mongo: 'mongo:4.4', mongoid: '5' }
           - { ruby: 'jruby-9.4.13.0', mongo: 'mongo:4.4', mongoid: '5' }
-          - { ruby: '2.6.6', mongo: 'mongo:4.4', mongoid: '6' }
-          - { ruby: '2.7.1', mongo: 'mongo:4.4', mongoid: '6' }
-          - { ruby: '3.0.5', mongo: 'mongo:4.4', mongoid: '6' }
-          - { ruby: '3.1.3', mongo: 'mongo:4.4', mongoid: '6' }
+          - { ruby: '3.1.7', mongo: 'mongo:4.4', mongoid: '6' }
+          - { ruby: '3.4.8', mongo: 'mongo:4.4', mongoid: '6' }
           - { ruby: 'jruby-9.4.13.0', mongo: 'mongo:4.4', mongoid: '6' }
-          - { ruby: '2.6.6', mongo: 'mongo:4.4', mongoid: '7', coverage: 'true' }
-          - { ruby: '2.7.1', mongo: 'mongo:4.4', mongoid: '7' }
-          - { ruby: '3.0.5', mongo: 'mongo:4.4', mongoid: '7' }
-          - { ruby: '3.1.3', mongo: 'mongo:4.4', mongoid: '7' }
+          - { ruby: '3.1.7', mongo: 'mongo:4.4', mongoid: '7', coverage: 'true' }
+          - { ruby: '3.4.8', mongo: 'mongo:4.4', mongoid: '7' }
           # - { ruby: 'jruby-9.4.13.0', mongo: 'mongo:4.4', mongoid: '7' }
-          - { ruby: '2.6.6', mongo: 'mongo:6.0', mongoid: '8' }
-          - { ruby: '2.7.1', mongo: 'mongo:7.0', mongoid: '8' }
-          - { ruby: '3.0.5', mongo: 'mongo:6.0', mongoid: '8' }
-          - { ruby: '3.1.3', mongo: 'mongo:7.0', mongoid: '8' }
-          - { ruby: '3.1.3', mongo: 'mongo:8.0', mongoid: '9' }
+          - { ruby: '3.1.7', mongo: 'mongo:6.0', mongoid: '8' }
+          - { ruby: '3.4.8', mongo: 'mongo:7.0', mongoid: '8' }
+          - { ruby: '3.4.8', mongo: 'mongo:8.0', mongoid: '9' }
+          - { ruby: '4.0.0', mongo: 'mongo:7.0', mongoid: '8' }
+          - { ruby: '4.0.0', mongo: 'mongo:8.0', mongoid: '9' }
           # - { ruby: 'jruby-9.4.13.0', mongo: 'mongo:8.0', mongoid: '8' }
         experimental: [false]
 
diff --git a/.rspec b/.rspec
index c99d2e7..775c62b 100644
--- a/.rspec
+++ b/.rspec
@@ -1 +1,2 @@
 --require spec_helper
+--format documentation
\ No newline at end of file
diff --git a/.rubocop.yml b/.rubocop.yml
index 9637e2f..19bce00 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -1,3 +1,7 @@
+AllCops:
+  SuggestExtensions: true
+  NewCops: enable
+
 Lint/RaiseException:
   Enabled: true
 
@@ -21,4 +25,6 @@ RSpec/LeakyConstantDeclaration:
 
 inherit_from: .rubocop_todo.yml
 
-require: rubocop-rspec
+plugins:
+  - rubocop-rspec
+  - rubocop-rake
diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index f7e101f..2751a13 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -1,54 +1,71 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2020-04-07 15:05:45 -0400 using RuboCop version 0.81.0.
+# on 2025-12-31 23:55:39 UTC using RuboCop version 1.81.1.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
-# Offense count: 3
-# Configuration parameters: Include.
-# Include: **/*.gemfile, **/Gemfile, **/gems.rb
-Bundler/DuplicatedGem:
+# Offense count: 1
+# Configuration parameters: Severity.
+Gemspec/RequiredRubyVersion:
   Exclude:
-    - 'Gemfile'
+    - 'mongoid-locker.gemspec'
 
-# Offense count: 4
-# Configuration parameters: IgnoredMethods.
-Metrics/AbcSize:
-  Max: 24
+# Offense count: 6
+# Configuration parameters: AllowedMethods.
+# AllowedMethods: enums
+Lint/ConstantDefinitionInBlock:
+  Exclude:
+    - 'spec/support/configurations_shared_context.rb'
+    - 'spec/test_examples_spec.rb'
 
-# Offense count: 11
-# Configuration parameters: CountComments, ExcludedMethods.
-# ExcludedMethods: refine
-Metrics/BlockLength:
-  Max: 290
+# Offense count: 8
+# Configuration parameters: AllowComments, AllowEmptyLambdas.
+Lint/EmptyBlock:
+  Exclude:
+    - 'spec/support/locker_is_included_shared_examples.rb'
 
-# Offense count: 5
-# Configuration parameters: CountComments, ExcludedMethods.
+# Offense count: 3
+# Configuration parameters: AllowedMethods, AllowedPatterns, CountRepeatedAttributes.
+Metrics/AbcSize:
+  Max: 27
+
+# Offense count: 6
+# Configuration parameters: CountComments, CountAsOne, AllowedMethods, AllowedPatterns.
 Metrics/MethodLength:
   Max: 31
 
 # Offense count: 1
-# Configuration parameters: CountComments.
+# Configuration parameters: CountComments, CountAsOne.
 Metrics/ModuleLength:
-  Max: 105
+  Max: 109
 
 # Offense count: 2
-# Configuration parameters: ExpectMatchingDefinition, Regex, IgnoreExecutableScripts, AllowedAcronyms.
+# Configuration parameters: ExpectMatchingDefinition, CheckDefinitionPathHierarchy, CheckDefinitionPathHierarchyRoots, Regex, IgnoreExecutableScripts, AllowedAcronyms.
+# CheckDefinitionPathHierarchyRoots: lib, spec, test, src
 # AllowedAcronyms: CLI, DSL, ACL, API, ASCII, CPU, CSS, DNS, EOF, GUID, HTML, HTTP, HTTPS, ID, IP, JSON, LHS, QPS, RAM, RHS, RPC, SLA, SMTP, SQL, SSH, TCP, TLS, TTL, UDP, UI, UID, UUID, URI, URL, UTF8, VM, XML, XMPP, XSRF, XSS
 Naming/FileName:
   Exclude:
+    - 'Rakefile.rb'
     - 'lib/mongoid-locker.rb'
     - 'spec/mongoid-locker_spec.rb'
 
 # Offense count: 1
-# Configuration parameters: NamePrefix, ForbiddenPrefixes, AllowedMethods, MethodDefinitionMacros.
-# NamePrefix: is_, has_, have_
-# ForbiddenPrefixes: is_, has_, have_
+# Configuration parameters: Mode, AllowedMethods, AllowedPatterns, AllowBangMethods, WaywardPredicates.
+# AllowedMethods: call
+# WaywardPredicates: nonzero?
+Naming/PredicateMethod:
+  Exclude:
+    - 'lib/mongoid/locker/wrapper.rb'
+
+# Offense count: 1
+# Configuration parameters: NamePrefix, ForbiddenPrefixes, AllowedMethods, MethodDefinitionMacros, UseSorbetSigs.
+# NamePrefix: is_, has_, have_, does_
+# ForbiddenPrefixes: is_, has_, have_, does_
 # AllowedMethods: is_a?
 # MethodDefinitionMacros: define_method, define_singleton_method
-Naming/PredicateName:
+Naming/PredicatePrefix:
   Exclude:
     - 'spec/**/*'
     - 'lib/mongoid/locker.rb'
@@ -56,28 +73,39 @@ Naming/PredicateName:
 # Offense count: 2
 RSpec/BeforeAfterAll:
   Exclude:
-    - 'spec/spec_helper.rb'
-    - 'spec/rails_helper.rb'
-    - 'spec/support/**/*.rb'
+    - '**/spec/spec_helper.rb'
+    - '**/spec/rails_helper.rb'
+    - '**/spec/support/**/*.rb'
     - 'spec/test_examples_spec.rb'
 
 # Offense count: 1
+# Configuration parameters: IgnoredMetadata.
 RSpec/DescribeClass:
   Exclude:
+    - '**/spec/features/**/*'
+    - '**/spec/requests/**/*'
+    - '**/spec/routing/**/*'
+    - '**/spec/system/**/*'
+    - '**/spec/views/**/*'
     - 'spec/test_examples_spec.rb'
 
-# Offense count: 8
-# Configuration parameters: Max.
+# Offense count: 9
+# Configuration parameters: CountAsOne.
 RSpec/ExampleLength:
+  Max: 11
+
+# Offense count: 5
+# This cop supports unsafe autocorrection (--autocorrect-all).
+RSpec/IncludeExamples:
   Exclude:
+    - 'spec/mongoid-locker_spec.rb'
     - 'spec/support/locker_is_included_shared_examples.rb'
-    - 'spec/test_examples_spec.rb'
+    - 'spec/support/locker_methods_shared_examples.rb'
 
-# Offense count: 1
-# Configuration parameters: CustomTransform, IgnoreMethods.
-RSpec/FilePath:
+# Offense count: 2
+RSpec/LetSetup:
   Exclude:
-    - 'spec/mongoid-locker_spec.rb'
+    - 'spec/support/populate_database_shared_context.rb'
 
 # Offense count: 12
 # Configuration parameters: .
@@ -85,30 +113,70 @@ RSpec/FilePath:
 RSpec/MessageSpies:
   EnforcedStyle: receive
 
+# Offense count: 12
+# Configuration parameters: AllowSubject.
+RSpec/MultipleMemoizedHelpers:
+  Max: 10
+
+# Offense count: 2
+# Configuration parameters: AllowedPatterns.
+# AllowedPatterns: ^expect_, ^assert_
+RSpec/NoExpectationExample:
+  Exclude:
+    - 'spec/support/locker_is_included_shared_examples.rb'
+
+# Offense count: 1
+RSpec/RemoveConst:
+  Exclude:
+    - 'spec/support/locker_helpers.rb'
+
+# Offense count: 1
+# Configuration parameters: CustomTransform, IgnoreMethods, IgnoreMetadata, InflectorPath, EnforcedInflector.
+# SupportedInflectors: default, active_support
+RSpec/SpecFilePathFormat:
+  Exclude:
+    - '**/spec/routing/**/*'
+    - 'spec/mongoid-locker_spec.rb'
+
 # Offense count: 1
 RSpec/SubjectStub:
   Exclude:
     - 'spec/support/delegated_methods_shared_examples.rb'
 
+# Offense count: 1
+# This cop supports unsafe autocorrection (--autocorrect-all).
+Style/CollectionQuerying:
+  Exclude:
+    - 'lib/mongoid/locker.rb'
+
 # Offense count: 2
+# Configuration parameters: AllowedConstants.
 Style/Documentation:
   Exclude:
     - 'spec/**/*'
     - 'test/**/*'
     - 'lib/mongoid/locker.rb'
 
+# Offense count: 4
+# This cop supports unsafe autocorrection (--autocorrect-all).
+# Configuration parameters: AllowSplatArgument.
+Style/HashConversion:
+  Exclude:
+    - 'spec/support/locker_is_included_shared_examples.rb'
+    - 'spec/support/locker_methods_shared_examples.rb'
+
 # Offense count: 2
-# Cop supports --auto-correct.
-# Configuration parameters: AutoCorrect, EnforcedStyle, IgnoredMethods.
+# This cop supports unsafe autocorrection (--autocorrect-all).
+# Configuration parameters: EnforcedStyle, AllowedMethods, AllowedPatterns.
 # SupportedStyles: predicate, comparison
 Style/NumericPredicate:
   Exclude:
     - 'spec/**/*'
     - 'lib/mongoid/locker.rb'
 
-# Offense count: 35
-# Cop supports --auto-correct.
-# Configuration parameters: AutoCorrect, AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, IgnoredPatterns.
+# Offense count: 7
+# This cop supports safe autocorrection (--autocorrect).
+# Configuration parameters: AllowHeredoc, AllowURI, AllowQualifiedName, URISchemes, IgnoreCopDirectives, AllowedPatterns, SplitStrings.
 # URISchemes: http, https
 Layout/LineLength:
   Max: 250
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 333ea05..bfe0d0e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,10 @@
 ## Changelog
 
-### 2.2.1 (Next)
+### 2.3.0 (Next)
 
+* [#109](https://github.com/mongoid/mongoid-locker/pull/109): Migrate Danger to use danger-pr-comment workflow - [@dblock](https://github.com/dblock).
+* [#109](https://github.com/mongoid/mongoid-locker/pull/109): Remove support for Ruby 2.x - [@dblock](https://github.com/dblock).
+* [#109](https://github.com/mongoid/mongoid-locker/pull/109): Add support for Ruby 4.0 - [@dblock](https://github.com/dblock).
 * Your contribution here.
 
 ### 2.2.0 (2025-06-22)
diff --git a/Dangerfile b/Dangerfile
index de2a4a0..f769387 100644
--- a/Dangerfile
+++ b/Dangerfile
@@ -1,3 +1,5 @@
 # frozen_string_literal: true
 
-danger.import_dangerfile(gem: 'mongoid-danger')
+danger.import_dangerfile(gem: 'danger-pr-comment')
+
+changelog.check!
diff --git a/Gemfile b/Gemfile
index 5925a0f..238f213 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,7 +3,7 @@
 source 'https://rubygems.org'
 gemspec
 
-case ENV['MONGOID_VERSION']
+case ENV.fetch('MONGOID_VERSION', nil)
 when /^9/
   gem 'mongoid', '~> 9.0'
 when /^8/
@@ -27,11 +27,16 @@ end
 group :development, :test do
   gem 'pry-byebug', platforms: :mri
 
+  gem 'bigdecimal', '1.3.5', platforms: :mri
+  gem 'danger', require: false
+  gem 'danger-changelog', require: false
+  gem 'danger-pr-comment', require: false
   gem 'mongoid-compatibility'
-  gem 'mongoid-danger', '~> 0.2.0'
   gem 'mongoid-history'
+  gem 'mutex_m'
   gem 'rspec', '~> 3.9'
-  gem 'rubocop', '0.81.0'
-  gem 'rubocop-rspec', '1.38.1'
+  gem 'rubocop', '1.81.1'
+  gem 'rubocop-rake'
+  gem 'rubocop-rspec'
   gem 'simplecov', require: false
 end
diff --git a/README.md b/README.md
index 09f312b..82e9c01 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ Document-level optimistic locking for MongoDB via Mongoid. Mongoid-Locker is an
 **NOTE:** Please refer to [1-x-stable](https://github.com/mongoid/mongoid-locker/tree/1-x-stable) branch for `1.x.x` documentation. See the [UPGRADING](UPGRADING.md) guide and [CHANGELOG](CHANGELOG.md) for an overview of the changes.
 
 [Tested](https://github.com/mongoid/mongoid-locker/actions) against:
-- MRI: `2.3.8`, `2.4.7`, `2.5.7`, `2.6.6`, `2.7.1`, `3.0.5`, `3.1.3`
+- MRI: `3.x`, `4.x`
 - JRuby `9.1.17.0`, `9.2.11.1`
 - Mongoid: `5`, `6`, `7`, `8`, `9`
 
diff --git a/lib/mongoid/locker.rb b/lib/mongoid/locker.rb
index 9f97d07..24be909 100644
--- a/lib/mongoid/locker.rb
+++ b/lib/mongoid/locker.rb
@@ -45,7 +45,7 @@ def secure_locking_name(_doc, opts)
       # @param opts [Hash] (see #with_lock)
       # @return [Float]
       def exponential_backoff(_doc, opts)
-        2**opts[:attempt] + rand
+        (2**opts[:attempt]) + rand
       end
 
       # Returns time in seconds remaining to complete the lock of the provided document. Makes requests to the database.
@@ -115,7 +115,9 @@ def included(klass)
         klass.locking_name_generator = locking_name_generator
 
         klass.delegate(*MODULE_METHODS, to: :class)
-        klass.singleton_class.delegate(*(methods(false) - MODULE_METHODS.flat_map { |method| [method, "#{method}=".to_sym] } - %i[included reset! configure]), to: self)
+        klass.singleton_class.delegate(*(methods(false) - MODULE_METHODS.flat_map do |method|
+          [method, :"#{method}="]
+        end - %i[included reset! configure]), to: self)
       end
     end
 
@@ -202,7 +204,10 @@ def unlock_all
       # @param locking_name_generator [Symbol]
       def locker(**params)
         invalid_parameters = params.keys - Mongoid::Locker.singleton_class.const_get('MODULE_METHODS')
-        raise Mongoid::Locker::Errors::InvalidParameter.new(self.class, invalid_parameters.first) unless invalid_parameters.empty?
+        unless invalid_parameters.empty?
+          raise Mongoid::Locker::Errors::InvalidParameter.new(self.class,
+                                                              invalid_parameters.first)
+        end
 
         params.each_pair do |key, value|
           send("#{key}=", value)
@@ -271,7 +276,10 @@ def acquire_lock(opts)
         opts[:attempt] += 1
         delay = self.class.send(backoff_algorithm, self, opts)
 
-        raise Errors::DocumentCouldNotGetLock.new(self.class, id) if delay >= maximum_backoff || opts[:attempt] >= opts[:retries]
+        if delay >= maximum_backoff || opts[:attempt] >= opts[:retries]
+          raise Errors::DocumentCouldNotGetLock.new(self.class,
+                                                    id)
+        end
 
         sleep delay
       end
diff --git a/lib/mongoid/locker/version.rb b/lib/mongoid/locker/version.rb
index 4fd7d2b..bbf3150 100644
--- a/lib/mongoid/locker/version.rb
+++ b/lib/mongoid/locker/version.rb
@@ -2,6 +2,6 @@
 
 module Mongoid
   module Locker
-    VERSION = '2.2.1'
+    VERSION = '2.3.0'
   end
 end
diff --git a/mongoid-locker.gemspec b/mongoid-locker.gemspec
index bdcfdcc..5760801 100644
--- a/mongoid-locker.gemspec
+++ b/mongoid-locker.gemspec
@@ -19,4 +19,5 @@ Gem::Specification.new do |s|
   s.require_paths = ['lib']
 
   s.add_dependency 'mongoid', '>= 5.0', '< 10'
+  s.metadata['rubygems_mfa_required'] = 'true'
 end
diff --git a/spec/integration/mongoid-history/mongoid_history_spec.rb b/spec/integration/mongoid-history/mongoid_history_spec.rb
index 7b0b006..e2f2cba 100644
--- a/spec/integration/mongoid-history/mongoid_history_spec.rb
+++ b/spec/integration/mongoid-history/mongoid_history_spec.rb
@@ -5,8 +5,7 @@
 # This replicates the exception reported at https://github.com/mongoid/mongoid-history/issues/238#issuecomment-1063155193
 # when mongoid-locker required 'forwardable' instead of relying on the
 # active support-provided delegation method
-RSpec.describe 'MongoidHistory' do # rubocop:disable RSpec/DescribeClass
-  # rubocop:disable RSpec/ExampleLength
+RSpec.describe 'MongoidHistory' do
   it 'does not raise an exception' do
     expect do
       Class.new do
@@ -20,5 +19,4 @@
       end
     end.not_to raise_exception
   end
-  # rubocop:enable RSpec/ExampleLength
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 17c4eb0..f3bc291 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -3,6 +3,7 @@
 ENV['RACK_ENV'] = 'test'
 
 require 'logger' # Required for compatibility with activesupport 7
+require 'bigdecimal' unless defined?(JRUBY_VERSION)
 
 if ENV['COVERAGE']
   require 'simplecov'