diff --git a/Gemfile b/Gemfile
index 20bf8670..6a4d9204 100644
--- a/Gemfile
+++ b/Gemfile
@@ -22,4 +22,4 @@ platforms :rbx do
   gem 'racc', '~> 1.4.10'
 end
 
-gem 'rails', "~> 4.0.0"
+gem 'rails', '~> 4.0.0'
diff --git a/test/integration/active_record/active_record_test.rb b/test/integration/active_record/active_record_test.rb
index 1747fc12..e65f7bb9 100644
--- a/test/integration/active_record/active_record_test.rb
+++ b/test/integration/active_record/active_record_test.rb
@@ -3,7 +3,7 @@ require 'fixtures/active_record'
 
 module ActiveModel
   class Serializer
-    class ActiveRecordTest < ActiveModel::TestCase
+    class ActiveRecordTest < Minitest::Test
       def setup
         @post = ARPost.first
       end
diff --git a/test/integration/generators/scaffold_controller_generator_test.rb b/test/integration/generators/scaffold_controller_generator_test.rb
index 52c8319f..dc6c4c49 100644
--- a/test/integration/generators/scaffold_controller_generator_test.rb
+++ b/test/integration/generators/scaffold_controller_generator_test.rb
@@ -16,7 +16,6 @@ class ScaffoldControllerGeneratorTest < Rails::Generators::TestCase
     run_generator
 
     assert_file 'app/controllers/accounts_controller.rb' do |content|
-      
       assert_instance_method :index, content do |m|
         assert_match /@accounts = Account\.all/, m
         assert_match /format.html/, m
@@ -60,8 +59,6 @@ class ScaffoldControllerGeneratorTest < Rails::Generators::TestCase
 
       assert_match(/def account_params/, content)
       assert_match(/params\.require\(:account\)\.permit\(:name, :description, :business_id\)/, content)
-
     end
-
   end
 end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index d60b8bc6..8ff5d1ed 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -4,6 +4,9 @@ require 'minitest/autorun'
 require 'active_model_serializers'
 require 'fixtures/poro'
 
+# Ensure backward compatibility with Minitest 4
+Minitest::Test = MiniTest::Unit::TestCase unless defined?(Minitest::Test)
+
 module TestHelper
   Routes = ActionDispatch::Routing::RouteSet.new
   Routes.draw do
diff --git a/test/unit/active_model/array_serializer/meta_test.rb b/test/unit/active_model/array_serializer/meta_test.rb
index 08b3db06..29b0cd7d 100644
--- a/test/unit/active_model/array_serializer/meta_test.rb
+++ b/test/unit/active_model/array_serializer/meta_test.rb
@@ -3,7 +3,7 @@ require 'active_model/serializer'
 
 module ActiveModel
   class ArraySerializer
-    class MetaTest < ActiveModel::TestCase
+    class MetaTest < Minitest::Test
       def setup
         @profile1 = Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' })
         @profile2 = Profile.new({ name: 'Name 2', description: 'Description 2', comments: 'Comments 2' })
diff --git a/test/unit/active_model/array_serializer/root_test.rb b/test/unit/active_model/array_serializer/root_test.rb
index 3453b7a2..6cade47a 100644
--- a/test/unit/active_model/array_serializer/root_test.rb
+++ b/test/unit/active_model/array_serializer/root_test.rb
@@ -2,7 +2,7 @@ require 'test_helper'
 
 module ActiveModel
   class ArraySerializer
-    class RootAsOptionTest < ActiveModel::TestCase
+    class RootAsOptionTest < Minitest::Test
       def setup
         @old_root = ArraySerializer._root
         @profile1 = Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' })
@@ -50,7 +50,7 @@ module ActiveModel
       end
     end
 
-    class RootInSerializerTest < ActiveModel::TestCase
+    class RootInSerializerTest < Minitest::Test
       def setup
         @old_root = ArraySerializer._root
         ArraySerializer._root = :in_serializer
diff --git a/test/unit/active_model/array_serializer/scope_test.rb b/test/unit/active_model/array_serializer/scope_test.rb
index b9c6034f..4cbefb5d 100644
--- a/test/unit/active_model/array_serializer/scope_test.rb
+++ b/test/unit/active_model/array_serializer/scope_test.rb
@@ -2,7 +2,7 @@ require 'test_helper'
 
 module ActiveModel
   class ArraySerializer
-    class ScopeTest < ActiveModel::TestCase
+    class ScopeTest < Minitest::Test
       def test_array_serializer_pass_options_to_items_serializers
         array = [Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' }),
                  Profile.new({ name: 'Name 2', description: 'Description 2', comments: 'Comments 2' })]
diff --git a/test/unit/active_model/array_serializer/serialization_test.rb b/test/unit/active_model/array_serializer/serialization_test.rb
index 51f2731a..3be85131 100644
--- a/test/unit/active_model/array_serializer/serialization_test.rb
+++ b/test/unit/active_model/array_serializer/serialization_test.rb
@@ -2,10 +2,10 @@ require 'test_helper'
 
 module ActiveModel
   class ArraySerializer
-    class BasicObjectsSerializationTest < ActiveModel::TestCase
+    class BasicObjectsSerializationTest < Minitest::Test
       def setup
         array = [1, 2, 3]
-        @serializer = ActiveModel::Serializer.serializer_for(array).new(array)
+        @serializer = Serializer.serializer_for(array).new(array)
       end
 
       def test_serializer_for_array_returns_appropriate_type
@@ -18,7 +18,7 @@ module ActiveModel
       end
     end
 
-    class ModelSerializationTest < ActiveModel::TestCase
+    class ModelSerializationTest < Minitest::Test
       def test_array_serializer_serializes_models
         array = [Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' }),
                  Profile.new({ name: 'Name 2', description: 'Description 2', comments: 'Comments 2' })]
diff --git a/test/unit/active_model/default_serializer_test.rb b/test/unit/active_model/default_serializer_test.rb
index 513953e0..fb64e565 100644
--- a/test/unit/active_model/default_serializer_test.rb
+++ b/test/unit/active_model/default_serializer_test.rb
@@ -2,7 +2,7 @@ require 'test_helper'
 
 module ActiveModel
   class DefaultSerializer
-    class Test < ActiveModel::TestCase
+    class Test < Minitest::Test
       def test_serialize_objects
         assert_equal(nil, DefaultSerializer.new(nil).serializable_object)
         assert_equal(1, DefaultSerializer.new(1).serializable_object)
diff --git a/test/unit/active_model/serializer/associations/build_serializer_test.rb b/test/unit/active_model/serializer/associations/build_serializer_test.rb
index eb0cf86f..2848badf 100644
--- a/test/unit/active_model/serializer/associations/build_serializer_test.rb
+++ b/test/unit/active_model/serializer/associations/build_serializer_test.rb
@@ -3,7 +3,7 @@ require 'test_helper'
 module ActiveModel
   class Serializer
     class Association
-      class BuildSerializerTest < ActiveModel::TestCase
+      class BuildSerializerTest < Minitest::Test
         def setup
           @association = Association::HasOne.new('post', serializer: PostSerializer)
           @post = Post.new({ title: 'Title 1', body: 'Body 1', date: '1/1/2000' })
diff --git a/test/unit/active_model/serializer/associations_test.rb b/test/unit/active_model/serializer/associations_test.rb
index 4e684b4d..4a1e0b22 100644
--- a/test/unit/active_model/serializer/associations_test.rb
+++ b/test/unit/active_model/serializer/associations_test.rb
@@ -2,7 +2,7 @@ require 'test_helper'
 
 module ActiveModel
   class Serializer
-    class AssociationsTest < ActiveModel::TestCase
+    class AssociationsTest < Minitest::Test
       def test_associations_inheritance
         inherited_serializer_klass = Class.new(PostSerializer) do
           has_many :users
diff --git a/test/unit/active_model/serializer/attributes_test.rb b/test/unit/active_model/serializer/attributes_test.rb
index 1cd6a1ca..5187cc55 100644
--- a/test/unit/active_model/serializer/attributes_test.rb
+++ b/test/unit/active_model/serializer/attributes_test.rb
@@ -2,7 +2,7 @@ require 'test_helper'
 
 module ActiveModel
   class Serializer
-    class AttributesTest < ActiveModel::TestCase
+    class AttributesTest < Minitest::Test
       def setup
         @profile = Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' })
         @profile_serializer = ProfileSerializer.new(@profile)
diff --git a/test/unit/active_model/serializer/config_test.rb b/test/unit/active_model/serializer/config_test.rb
index 2ade1fd0..a7f20976 100644
--- a/test/unit/active_model/serializer/config_test.rb
+++ b/test/unit/active_model/serializer/config_test.rb
@@ -3,7 +3,7 @@ require 'test_helper'
 module ActiveModel
   class Serializer
     class Config
-      class Test < ActiveModel::TestCase
+      class Test < Minitest::Test
         def test_config_const_is_an_instance_of_config
           assert_kind_of Config, CONFIG
         end
@@ -30,9 +30,9 @@ module ActiveModel
         end
       end
 
-      class ConfigTest < ActiveModel::TestCase
+      class ConfigTest < Minitest::Test
         def test_setup
-          ActiveModel::Serializer.setup do |config|
+          Serializer.setup do |config|
             config.a = 'v1'
             config.b = 'v2'
           end
@@ -44,7 +44,7 @@ module ActiveModel
         end
 
         def test_config_accessors
-          ActiveModel::Serializer.setup do |config|
+          Serializer.setup do |config|
             config.foo = 'v1'
             config.bar = 'v2'
           end
@@ -63,7 +63,7 @@ module ActiveModel
         end
       end
 
-      class ApplyConfigTest < ActiveModel::TestCase
+      class ApplyConfigTest < Minitest::Test
         def test_apply_config_to_associations
           CONFIG.embed     = :ids
           CONFIG.embed_in_root = true
diff --git a/test/unit/active_model/serializer/filter_test.rb b/test/unit/active_model/serializer/filter_test.rb
index bf33b5e7..34dee864 100644
--- a/test/unit/active_model/serializer/filter_test.rb
+++ b/test/unit/active_model/serializer/filter_test.rb
@@ -2,7 +2,7 @@ require 'test_helper'
 
 module ActiveModel
   class Serializer
-    class FilterAttributesTest < ActiveModel::TestCase
+    class FilterAttributesTest < Minitest::Test
       def setup
         @profile = Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' })
         @profile_serializer = ProfileSerializer.new(@profile)
@@ -20,7 +20,7 @@ module ActiveModel
       end
     end
 
-    class FilterAssociationsTest < ActiveModel::TestCase
+    class FilterAssociationsTest < Minitest::Test
       def setup
         @association = PostSerializer._associations[:comments]
         @old_association = @association.dup
diff --git a/test/unit/active_model/serializer/has_many_test.rb b/test/unit/active_model/serializer/has_many_test.rb
index 8d05d7b1..460996c4 100644
--- a/test/unit/active_model/serializer/has_many_test.rb
+++ b/test/unit/active_model/serializer/has_many_test.rb
@@ -2,7 +2,7 @@ require 'test_helper'
 
 module ActiveModel
   class Serializer
-    class HasManyTest < ActiveModel::TestCase
+    class HasManyTest < Minitest::Test
       def setup
         @association = PostSerializer._associations[:comments]
         @old_association = @association.dup
@@ -128,7 +128,7 @@ module ActiveModel
       def test_associations_using_a_given_serializer
         @association.embed = :ids
         @association.embed_in_root = true
-        @association.serializer_from_options = Class.new(ActiveModel::Serializer) do
+        @association.serializer_from_options = Class.new(Serializer) do
           def content
             object.read_attribute_for_serialization(:content) + '!'
           end
@@ -145,7 +145,7 @@ module ActiveModel
       def test_associations_embedding_ids_using_a_given_array_serializer
         @association.embed = :ids
         @association.embed_in_root = true
-        @association.serializer_from_options = Class.new(ActiveModel::ArraySerializer) do
+        @association.serializer_from_options = Class.new(ArraySerializer) do
           def serializable_object
             { my_content: ['fake'] }
           end
@@ -158,7 +158,7 @@ module ActiveModel
       end
 
       def test_associations_embedding_objects_using_a_given_array_serializer
-        @association.serializer_from_options = Class.new(ActiveModel::ArraySerializer) do
+        @association.serializer_from_options = Class.new(ArraySerializer) do
           def serializable_object
             { my_content: ['fake'] }
           end
diff --git a/test/unit/active_model/serializer/has_one_test.rb b/test/unit/active_model/serializer/has_one_test.rb
index a090a15c..fbe1e12d 100644
--- a/test/unit/active_model/serializer/has_one_test.rb
+++ b/test/unit/active_model/serializer/has_one_test.rb
@@ -2,7 +2,7 @@ require 'test_helper'
 
 module ActiveModel
   class Serializer
-    class HasOneTest < ActiveModel::TestCase
+    class HasOneTest < Minitest::Test
       def setup
         @association = UserSerializer._associations[:profile]
         @old_association = @association.dup
@@ -119,7 +119,7 @@ module ActiveModel
       def test_associations_embedding_ids_using_a_given_serializer
         @association.embed = :ids
         @association.embed_in_root = true
-        @association.serializer_from_options = Class.new(ActiveModel::Serializer) do
+        @association.serializer_from_options = Class.new(Serializer) do
           def name
             'fake'
           end
@@ -134,7 +134,7 @@ module ActiveModel
       end
 
       def test_associations_embedding_objects_using_a_given_serializer
-        @association.serializer_from_options = Class.new(ActiveModel::Serializer) do
+        @association.serializer_from_options = Class.new(Serializer) do
           def name
             'fake'
           end
diff --git a/test/unit/active_model/serializer/meta_test.rb b/test/unit/active_model/serializer/meta_test.rb
index c5d00bf6..8f8d49c8 100644
--- a/test/unit/active_model/serializer/meta_test.rb
+++ b/test/unit/active_model/serializer/meta_test.rb
@@ -2,7 +2,7 @@ require 'test_helper'
 
 module ActiveModel
   class Serializer
-    class MetaTest < ActiveModel::TestCase
+    class MetaTest < Minitest::Test
       def setup
         @profile = Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' })
       end
diff --git a/test/unit/active_model/serializer/root_test.rb b/test/unit/active_model/serializer/root_test.rb
index e3a160ce..868e1417 100644
--- a/test/unit/active_model/serializer/root_test.rb
+++ b/test/unit/active_model/serializer/root_test.rb
@@ -2,7 +2,7 @@ require 'test_helper'
 
 module ActiveModel
   class Serializer
-    class RootAsOptionTest < ActiveModel::TestCase
+    class RootAsOptionTest < Minitest::Test
       def setup
         @old_root = ProfileSerializer._root
         @profile = Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' })
@@ -70,7 +70,7 @@ module ActiveModel
       end
     end
 
-    class RootInSerializerTest < ActiveModel::TestCase
+    class RootInSerializerTest < Minitest::Test
       def setup
         @old_root = ProfileSerializer._root
         ProfileSerializer._root = :in_serializer
diff --git a/test/unit/active_model/serializer/scope_test.rb b/test/unit/active_model/serializer/scope_test.rb
index 298b686e..f88aa1f6 100644
--- a/test/unit/active_model/serializer/scope_test.rb
+++ b/test/unit/active_model/serializer/scope_test.rb
@@ -2,7 +2,7 @@ require 'test_helper'
 
 module ActiveModel
   class Serializer
-    class ScopeTest < ActiveModel::TestCase
+    class ScopeTest < Minitest::Test
       def setup
         @serializer = ProfileSerializer.new(nil, scope: current_user)
       end
@@ -18,7 +18,7 @@ module ActiveModel
       end
     end
 
-    class NestedScopeTest < ActiveModel::TestCase
+    class NestedScopeTest < Minitest::Test
       def setup
         @association = UserSerializer._associations[:profile]
         @old_association = @association.dup
@@ -31,7 +31,7 @@ module ActiveModel
       end
 
       def test_scope_passed_through
-        @association.serializer_from_options = Class.new(ActiveModel::Serializer) do
+        @association.serializer_from_options = Class.new(Serializer) do
           def name
             scope
           end