diff --git a/.rubocop.yml b/.rubocop.yml
index d808271ce..d57fdc880 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -8,6 +8,42 @@ AllCops:
   DisplayCopNames: true
   DisplayStyleGuide: true
 
+Style/IndentationConsistency:
+  Exclude:
+    - lib/active_model/serializer/adapter.rb
+    - lib/active_model/serializer/adapter/flatten_json.rb
+    - lib/active_model/serializer/adapter/fragment_cache.rb
+    - lib/active_model/serializer/adapter/json.rb
+    - lib/active_model/serializer/adapter/json/fragment_cache.rb
+    - lib/active_model/serializer/adapter/json_api.rb
+    - lib/active_model/serializer/adapter/json_api/fragment_cache.rb
+    - lib/active_model/serializer/adapter/json_api/pagination_links.rb
+    - lib/active_model/serializer/adapter/null.rb
+
+Style/IndentationWidth:
+  Exclude:
+    - lib/active_model/serializer/adapter.rb
+    - lib/active_model/serializer/adapter/flatten_json.rb
+    - lib/active_model/serializer/adapter/fragment_cache.rb
+    - lib/active_model/serializer/adapter/json.rb
+    - lib/active_model/serializer/adapter/json/fragment_cache.rb
+    - lib/active_model/serializer/adapter/json_api.rb
+    - lib/active_model/serializer/adapter/json_api/fragment_cache.rb
+    - lib/active_model/serializer/adapter/json_api/pagination_links.rb
+    - lib/active_model/serializer/adapter/null.rb
+
+Style/AccessModifierIndentation:
+  Exclude:
+    - lib/active_model/serializer/adapter.rb
+    - lib/active_model/serializer/adapter/flatten_json.rb
+    - lib/active_model/serializer/adapter/fragment_cache.rb
+    - lib/active_model/serializer/adapter/json.rb
+    - lib/active_model/serializer/adapter/json/fragment_cache.rb
+    - lib/active_model/serializer/adapter/json_api.rb
+    - lib/active_model/serializer/adapter/json_api/fragment_cache.rb
+    - lib/active_model/serializer/adapter/json_api/pagination_links.rb
+    - lib/active_model/serializer/adapter/null.rb
+
 Lint/NestedMethodDefinition:
   Enabled: false
   Exclude:
diff --git a/lib/active_model/serializable_resource.rb b/lib/active_model/serializable_resource.rb
index feae1e8e7..d3565f9a5 100644
--- a/lib/active_model/serializable_resource.rb
+++ b/lib/active_model/serializable_resource.rb
@@ -76,7 +76,7 @@ def serializer?
     private
 
     ActiveModelSerializers.silence_warnings do
-    attr_reader :resource, :adapter_opts, :serializer_opts
+      attr_reader :resource, :adapter_opts, :serializer_opts
     end
   end
 end
diff --git a/lib/active_model/serializer/adapter.rb b/lib/active_model/serializer/adapter.rb
index 74a997fc7..2354f7291 100644
--- a/lib/active_model/serializer/adapter.rb
+++ b/lib/active_model/serializer/adapter.rb
@@ -4,11 +4,11 @@ class Adapter
       UnknownAdapterError = Class.new(ArgumentError)
       ADAPTER_MAP = {}
       extend ActiveSupport::Autoload
-      require 'active_model/serializer/adapter/json'
-      require 'active_model/serializer/adapter/json_api'
-      autoload :FlattenJson
-      autoload :Null
       autoload :FragmentCache
+      autoload :Json
+      autoload :JsonApi
+      autoload :Null
+      autoload :FlattenJson
 
       def self.create(resource, options = {})
         override = options.delete(:adapter)
diff --git a/lib/active_model/serializer/adapter/flatten_json.rb b/lib/active_model/serializer/adapter/flatten_json.rb
index 7ed570349..0c10f3e6e 100644
--- a/lib/active_model/serializer/adapter/flatten_json.rb
+++ b/lib/active_model/serializer/adapter/flatten_json.rb
@@ -1,7 +1,4 @@
-module ActiveModel
-  class Serializer
-    class Adapter
-      class FlattenJson < Json
+class ActiveModel::Serializer::Adapter::FlattenJson < ActiveModel::Serializer::Adapter::Json
         def serializable_hash(options = {})
           super
           @result
@@ -13,7 +10,4 @@ def serializable_hash(options = {})
         def include_meta(json)
           json
         end
-      end
-    end
-  end
 end
diff --git a/lib/active_model/serializer/adapter/fragment_cache.rb b/lib/active_model/serializer/adapter/fragment_cache.rb
index 8463b5a23..13558c088 100644
--- a/lib/active_model/serializer/adapter/fragment_cache.rb
+++ b/lib/active_model/serializer/adapter/fragment_cache.rb
@@ -1,7 +1,4 @@
-module ActiveModel
-  class Serializer
-    class Adapter
-      class FragmentCache
+class ActiveModel::Serializer::Adapter::FragmentCache
         attr_reader :serializer
 
         def initialize(adapter, serializer, options)
@@ -75,7 +72,4 @@ def fragment_serializer(name, klass)
         def to_valid_const_name(name)
           name.gsub('::', '_')
         end
-      end
-    end
-  end
 end
diff --git a/lib/active_model/serializer/adapter/json.rb b/lib/active_model/serializer/adapter/json.rb
index b3fa6e9c6..2c0b6455c 100644
--- a/lib/active_model/serializer/adapter/json.rb
+++ b/lib/active_model/serializer/adapter/json.rb
@@ -1,9 +1,7 @@
-require 'active_model/serializer/adapter/json/fragment_cache'
+class ActiveModel::Serializer::Adapter::Json < ActiveModel::Serializer::Adapter
+        extend ActiveSupport::Autoload
+        autoload :FragmentCache
 
-module ActiveModel
-  class Serializer
-    class Adapter
-      class Json < Adapter
         def serializable_hash(options = nil)
           options ||= {}
           if serializer.respond_to?(:each)
@@ -44,9 +42,6 @@ def serializable_hash(options = nil)
         end
 
         def fragment_cache(cached_hash, non_cached_hash)
-          Json::FragmentCache.new().fragment_cache(cached_hash, non_cached_hash)
+          ActiveModel::Serializer::Adapter::Json::FragmentCache.new().fragment_cache(cached_hash, non_cached_hash)
         end
-      end
-    end
-  end
 end
diff --git a/lib/active_model/serializer/adapter/json/fragment_cache.rb b/lib/active_model/serializer/adapter/json/fragment_cache.rb
index 846a216ff..5e687241d 100644
--- a/lib/active_model/serializer/adapter/json/fragment_cache.rb
+++ b/lib/active_model/serializer/adapter/json/fragment_cache.rb
@@ -1,14 +1,5 @@
-require 'active_model/serializer/adapter/fragment_cache'
-module ActiveModel
-  class Serializer
-    class Adapter
-      class Json < Adapter
-        class FragmentCache
+class ActiveModel::Serializer::Adapter::Json::FragmentCache
           def fragment_cache(cached_hash, non_cached_hash)
             non_cached_hash.merge cached_hash
           end
-        end
-      end
-    end
-  end
 end
diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index 48f8173c8..bba8cc1d9 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -1,10 +1,8 @@
-require 'active_model/serializer/adapter/json_api/fragment_cache'
-require 'active_model/serializer/adapter/json_api/pagination_links'
+class ActiveModel::Serializer::Adapter::JsonApi < ActiveModel::Serializer::Adapter
+        extend ActiveSupport::Autoload
+        autoload :PaginationLinks
+        autoload :FragmentCache
 
-module ActiveModel
-  class Serializer
-    class Adapter
-      class JsonApi < Adapter
         def initialize(serializer, options = {})
           super
           @hash = { data: [] }
@@ -39,11 +37,9 @@ def serializable_hash(options = nil)
 
         def fragment_cache(cached_hash, non_cached_hash)
           root = false if @options.include?(:include)
-          JsonApi::FragmentCache.new().fragment_cache(root, cached_hash, non_cached_hash)
+          ActiveModel::Serializer::Adapter::JsonApi::FragmentCache.new().fragment_cache(root, cached_hash, non_cached_hash)
         end
 
-        private
-
         def add_relationships(resource, name, serializers)
           resource[:relationships] ||= {}
           resource[:relationships][name] ||= { data: [] }
@@ -169,17 +165,14 @@ def add_links(options)
           end
         end
 
-        def add_pagination_links(links, collection, options)
-          pagination_links = JsonApi::PaginationLinks.new(collection, options[:context]).serializable_hash(options)
+        def add_pagination_links(links, resources, options)
+          pagination_links = ActiveModel::Serializer::Adapter::JsonApi::PaginationLinks.new(resources, options[:context]).serializable_hash(options)
           links.update(pagination_links)
         end
 
-        def is_paginated?(collection)
-          collection.respond_to?(:current_page) &&
-            collection.respond_to?(:total_pages) &&
-            collection.respond_to?(:size)
+        def is_paginated?(resource)
+          resource.respond_to?(:current_page) &&
+            resource.respond_to?(:total_pages) &&
+            resource.respond_to?(:size)
         end
-      end
-    end
-  end
 end
diff --git a/lib/active_model/serializer/adapter/json_api/fragment_cache.rb b/lib/active_model/serializer/adapter/json_api/fragment_cache.rb
index 070371ac7..ab3481307 100644
--- a/lib/active_model/serializer/adapter/json_api/fragment_cache.rb
+++ b/lib/active_model/serializer/adapter/json_api/fragment_cache.rb
@@ -1,9 +1,4 @@
-require 'active_model/serializer/adapter/fragment_cache'
-module ActiveModel
-  class Serializer
-    class Adapter
-      class JsonApi < Adapter
-        class FragmentCache
+class ActiveModel::Serializer::Adapter::JsonApi::FragmentCache
           def fragment_cache(root, cached_hash, non_cached_hash)
             hash              = {}
             core_cached       = cached_hash.first
@@ -15,8 +10,4 @@ def fragment_cache(root, cached_hash, non_cached_hash)
 
             hash.deep_merge no_root_non_cache.deep_merge no_root_cache
           end
-        end
-      end
-    end
-  end
 end
diff --git a/lib/active_model/serializer/adapter/json_api/pagination_links.rb b/lib/active_model/serializer/adapter/json_api/pagination_links.rb
index 55e3280b8..8661f3b14 100644
--- a/lib/active_model/serializer/adapter/json_api/pagination_links.rb
+++ b/lib/active_model/serializer/adapter/json_api/pagination_links.rb
@@ -1,8 +1,4 @@
-module ActiveModel
-  class Serializer
-    class Adapter
-      class JsonApi < Adapter
-        class PaginationLinks
+class ActiveModel::Serializer::Adapter::JsonApi::PaginationLinks
           FIRST_PAGE = 1
 
           attr_reader :collection, :context
@@ -51,8 +47,4 @@ def original_url
           def query_parameters
             @query_parameters ||= context.query_parameters
           end
-        end
-      end
-    end
-  end
 end
diff --git a/lib/active_model/serializer/adapter/null.rb b/lib/active_model/serializer/adapter/null.rb
index 1728f88ed..78f9b8e3b 100644
--- a/lib/active_model/serializer/adapter/null.rb
+++ b/lib/active_model/serializer/adapter/null.rb
@@ -1,11 +1,5 @@
-module ActiveModel
-  class Serializer
-    class Adapter
-      class Null < Adapter
+class ActiveModel::Serializer::Adapter::Null < ActiveModel::Serializer::Adapter
         def serializable_hash(options = nil)
           {}
         end
-      end
-    end
-  end
 end
diff --git a/lib/active_model/serializer/fieldset.rb b/lib/active_model/serializer/fieldset.rb
index 30e683344..935aea81a 100644
--- a/lib/active_model/serializer/fieldset.rb
+++ b/lib/active_model/serializer/fieldset.rb
@@ -18,7 +18,7 @@ def fields_for(serializer)
       private
 
       ActiveModelSerializers.silence_warnings do
-      attr_reader :raw_fields, :root
+        attr_reader :raw_fields, :root
       end
 
       def parsed_fields
diff --git a/test/action_controller/serialization_scope_name_test.rb b/test/action_controller/serialization_scope_name_test.rb
index 6e2b15e6e..51abf1080 100644
--- a/test/action_controller/serialization_scope_name_test.rb
+++ b/test/action_controller/serialization_scope_name_test.rb
@@ -25,7 +25,7 @@ def render_new_user
     end
   end
 
- tests UserTestController
+  tests UserTestController
 
   def test_default_scope_name
     get :render_new_user
diff --git a/test/serializers/adapter_for_test.rb b/test/serializers/adapter_for_test.rb
index 39666bc32..076887ec2 100644
--- a/test/serializers/adapter_for_test.rb
+++ b/test/serializers/adapter_for_test.rb
@@ -155,12 +155,11 @@ def test_inherited_adapter_hooks_register_subclass_of_registered_adapter
         assert_equal ActiveModel::Serializer::Adapter.get(:my_adapter), my_adapter
         assert_equal ActiveModel::Serializer::Adapter.get(:my_subclassed_adapter), my_subclassed_adapter
       ensure
-        ActiveModel::Serializer::Adapter::ADAPTER_MAP.delete("my_adapter".freeze)
-        ActiveModel::Serializer::Adapter::ADAPTER_MAP.delete("my_subclassed_adapter".freeze)
+        ActiveModel::Serializer::Adapter::ADAPTER_MAP.delete('my_adapter'.freeze)
+        ActiveModel::Serializer::Adapter::ADAPTER_MAP.delete('my_subclassed_adapter'.freeze)
         Object.send(:remove_const, :MyAdapter)
         Object.send(:remove_const, :MySubclassedAdapter)
       end
-
     end
   end
 end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 7872d86a7..a1916b211 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -31,12 +31,12 @@
 # eager load autoloaded adapters
 # rubocop:disable Lint/Void
 require 'active_model/serializer/adapter'
+ActiveModel::Serializer::Adapter
 ActiveModel::Serializer::Adapter::Null
 ActiveModel::Serializer::Adapter::Json
 ActiveModel::Serializer::Adapter::FlattenJson
 ActiveModel::Serializer::Adapter::JsonApi
 # rubocop:enable Lint/Void
-require 'active_model/serializer/adapter'
 
 require 'support/stream_capture'