diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e5a589bd8..acd6d9bbe 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -13,26 +13,36 @@ jobs:
       matrix:
         include:
           # Recent Rubies and Rails
-          - ruby-version: '3.3'
+          - ruby-version: '3.4'
+            rails-version: '8.1'
+          - ruby-version: '3.4'
             rails-version: '8.0'
-          - ruby-version: '3.2'
+          - ruby-version: '3.4'
+            rails-version: '7.2'
+          - ruby-version: '3.3'
             rails-version: '8.0'
+          - ruby-version: '3.3'
+            rails-version: '7.2'
+          - ruby-version: '3.3'
+            rails-version: '7.1'
           - ruby-version: '3.2'
             rails-version: '7.2'
           - ruby-version: '3.2'
             rails-version: '7.1'
+          - ruby-version: '3.2'
+            rails-version: '7.0'
           - ruby-version: '3.1'
             rails-version: '7.1'
           - ruby-version: '3.0'
-            rails-version: '7.1'
+            rails-version: '7.0'
           - ruby-version: '2.7'
-            rails-version: '7.1'
+            rails-version: '6.1'
+          - ruby-version: '2.7'
+            rails-version: '6.0'
           - ruby-version: '2.6'
             rails-version: '6.1'
           - ruby-version: '2.6'
             rails-version: '6.0'
-          - ruby-version: '2.7'
-            rails-version: '6.0'
           - ruby-version: '2.6'
             rails-version: '5.2'
           # Old Rubies and Rails
diff --git a/Gemfile b/Gemfile
index a9c26e9b6..83693517b 100644
--- a/Gemfile
+++ b/Gemfile
@@ -82,6 +82,7 @@ group :test do
     end
   end
   gem 'codeclimate-test-reporter', require: false
+  gem 'json', '< 2.10', require: false
   gem 'm', '~> 1.5'
   gem 'pry', '>= 0.10'
   gem 'byebug', '~> 8.2' if RUBY_VERSION < '2.2'
@@ -96,6 +97,11 @@ group :development, :test do
     gem 'rubocop-minitest', '~> 0.31.0', require: false
     gem 'rubocop-rails', '~> 2.20.0', require: false
     gem 'rubocop-rake', '~> 0.6.0', require: false
+
+    if RUBY_VERSION >= '3.4.0'
+      gem 'ostruct', require: false
+      gem 'mutex_m', require: false
+    end
   end
   if version <= '5.0'
     gem 'loofah', '< 2.21.0'
diff --git a/lib/active_model/serializer.rb b/lib/active_model/serializer.rb
index 5e3477905..118098f93 100644
--- a/lib/active_model/serializer.rb
+++ b/lib/active_model/serializer.rb
@@ -13,6 +13,9 @@
 # reified when subclassed to decorate a resource.
 module ActiveModel
   class Serializer
+    class_attribute :config
+    self.config = ActiveSupport::OrderedOptions.new
+
     undef_method :select, :display # These IO methods, which are mixed into Kernel,
     # sometimes conflict with attribute names. We don't need these IO methods.
 
@@ -30,7 +33,6 @@ class Serializer
       autoload :HasOneReflection
       autoload :HasManyReflection
     end
-    include ActiveSupport::Configurable
     include Caching
 
     # @param resource [ActiveRecord::Base, ActiveModelSerializers::Model]
diff --git a/test/serializers/reflection_test.rb b/test/serializers/reflection_test.rb
index bb90e81c8..b8998b189 100644
--- a/test/serializers/reflection_test.rb
+++ b/test/serializers/reflection_test.rb
@@ -383,7 +383,10 @@ def test_no_href_in_vanilla_reflection
         exception = assert_raise(NoMethodError) do
           reflection.instance_eval(&link)
         end
-        assert_match(/undefined method `href'/, exception.message)
+
+        expected = RUBY_VERSION >= '3.4.0' ? /undefined method 'href'/ : /undefined method `href'/
+
+        assert_match(expected, exception.message)
       end
 
       # rubocop:disable Metrics/AbcSize
diff --git a/test/support/isolated_unit.rb b/test/support/isolated_unit.rb
index af80f601b..2566d2685 100644
--- a/test/support/isolated_unit.rb
+++ b/test/support/isolated_unit.rb
@@ -38,6 +38,7 @@
 # It is also good to know what is the bare minimum to get
 # Rails booted up.
 require 'bundler/setup' unless defined?(Bundler)
+require 'logger'
 require 'active_support'
 require 'active_support/core_ext/string/access'
 
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 7d8ca63e3..7da8a09a6 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -4,6 +4,7 @@
 ENV['RAILS_ENV'] = 'test'
 require 'bundler/setup'
 
+require 'logger'
 require 'pry'
 require 'timecop'
 require 'rails'