diff --git a/CHANGELOG.md b/CHANGELOG.md
index f2a8e2bd2..65c350460 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@ Features:
 Fixes:
 - [#1710](https://github.com/rails-api/active_model_serializers/pull/1710) Prevent association loading when `include_data` option
   is set to `false`. (@groyoh)
+- [#1747](https://github.com/rails-api/active_model_serializers/pull/1747) Improve jsonapi mime type registration for Rails 5 (@remear)
 
 Misc:
 - [#1734](https://github.com/rails-api/active_model_serializers/pull/1734) Adds documentation for conditional attribute (@lambda2)
diff --git a/lib/active_model_serializers/register_jsonapi_renderer.rb b/lib/active_model_serializers/register_jsonapi_renderer.rb
index 4a532b445..813503f5c 100644
--- a/lib/active_model_serializers/register_jsonapi_renderer.rb
+++ b/lib/active_model_serializers/register_jsonapi_renderer.rb
@@ -22,43 +22,54 @@
 # render jsonapi: model
 #
 # No wrapper format needed as it does not apply (i.e. no `wrap_parameters format: [jsonapi]`)
-
 module ActiveModelSerializers::Jsonapi
   MEDIA_TYPE = 'application/vnd.api+json'.freeze
   HEADERS = {
     response: { 'CONTENT_TYPE'.freeze => MEDIA_TYPE },
     request:  { 'ACCEPT'.freeze => MEDIA_TYPE }
   }.freeze
+
+  def self.install
+    # actionpack/lib/action_dispatch/http/mime_types.rb
+    Mime::Type.register MEDIA_TYPE, :jsonapi
+
+    if Rails::VERSION::MAJOR >= 5
+      ActionDispatch::Request.parameter_parsers[:jsonapi] = parser
+    else
+      ActionDispatch::ParamsParser::DEFAULT_PARSERS[Mime[:jsonapi]] = parser
+    end
+
+    # ref https://github.com/rails/rails/pull/21496
+    ActionController::Renderers.add :jsonapi do |json, options|
+      json = serialize_jsonapi(json, options).to_json(options) unless json.is_a?(String)
+      self.content_type ||= Mime[:jsonapi]
+      self.response_body = json
+    end
+  end
+
+  # Proposal: should actually deserialize the JSON API params
+  # to the hash format expected by `ActiveModel::Serializers::JSON`
+  # actionpack/lib/action_dispatch/http/parameters.rb
+  def self.parser
+    lambda do |body|
+      data = JSON.parse(body)
+      data = { :_json => data } unless data.is_a?(Hash)
+      data.with_indifferent_access
+    end
+  end
+
   module ControllerSupport
     def serialize_jsonapi(json, options)
       options[:adapter] = :json_api
-      options.fetch(:serialization_context) { options[:serialization_context] = ActiveModelSerializers::SerializationContext.new(request) }
+      options.fetch(:serialization_context) do
+        options[:serialization_context] = ActiveModelSerializers::SerializationContext.new(request)
+      end
       get_serializer(json, options)
     end
   end
 end
 
-# actionpack/lib/action_dispatch/http/mime_types.rb
-Mime::Type.register ActiveModelSerializers::Jsonapi::MEDIA_TYPE, :jsonapi
-
-parsers = Rails::VERSION::MAJOR >= 5 ? ActionDispatch::Http::Parameters : ActionDispatch::ParamsParser
-media_type = Mime::Type.lookup(ActiveModelSerializers::Jsonapi::MEDIA_TYPE)
-
-# Proposal: should actually deserialize the JSON API params
-# to the hash format expected by `ActiveModel::Serializers::JSON`
-# actionpack/lib/action_dispatch/http/parameters.rb
-parsers::DEFAULT_PARSERS[media_type] = lambda do |body|
-  data = JSON.parse(body)
-  data = { :_json => data } unless data.is_a?(Hash)
-  data.with_indifferent_access
-end
-
-# ref https://github.com/rails/rails/pull/21496
-ActionController::Renderers.add :jsonapi do |json, options|
-  json = serialize_jsonapi(json, options).to_json(options) unless json.is_a?(String)
-  self.content_type ||= media_type
-  self.response_body = json
-end
+ActiveModelSerializers::Jsonapi.install
 
 ActiveSupport.on_load(:action_controller) do
   include ActiveModelSerializers::Jsonapi::ControllerSupport
diff --git a/test/action_controller/json_api/linked_test.rb b/test/action_controller/json_api/linked_test.rb
index 5a1e3bc36..6e59e4ea3 100644
--- a/test/action_controller/json_api/linked_test.rb
+++ b/test/action_controller/json_api/linked_test.rb
@@ -3,9 +3,8 @@
 module ActionController
   module Serialization
     class JsonApi
-      class LinkedTest < ActionController::TestCase
+      class LinkedTest < ActionDispatch::IntegrationTest
         class LinkedTestController < ActionController::Base
-          require 'active_model_serializers/register_jsonapi_renderer'
           def setup_post
             ActionController::Base.cache_store.clear
             @role1 = Role.new(id: 1, name: 'admin')
@@ -39,62 +38,68 @@ def setup_post
 
           def render_resource_without_include
             setup_post
-            render jsonapi: @post
+            render json: @post
           end
 
           def render_resource_with_include
             setup_post
-            render jsonapi: @post, include: [:author]
+            render json: @post, adapter: :json_api, include: [:author]
           end
 
           def render_resource_with_include_of_custom_key_by_original
             setup_post
-            render jsonapi: @post, include: [:reviews], serializer: PostWithCustomKeysSerializer
+            render json: @post, adapter: :json_api, include: [:reviews], serializer: PostWithCustomKeysSerializer
           end
 
           def render_resource_with_nested_include
             setup_post
-            render jsonapi: @post, include: [comments: [:author]]
+            render json: @post, adapter: :json_api, include: [comments: [:author]]
           end
 
           def render_resource_with_nested_has_many_include_wildcard
             setup_post
-            render jsonapi: @post, include: 'author.*'
+            render json: @post, adapter: :json_api, include: 'author.*'
           end
 
           def render_resource_with_missing_nested_has_many_include
             setup_post
             @post.author = @author2 # author2 has no roles.
-            render jsonapi: @post, include: [author: [:roles]]
+            render json: @post, adapter: :json_api, include: [author: [:roles]]
           end
 
           def render_collection_with_missing_nested_has_many_include
             setup_post
             @post.author = @author2
-            render jsonapi: [@post, @post2], include: [author: [:roles]]
+            render json: [@post, @post2], adapter: :json_api, include: [author: [:roles]]
           end
 
           def render_collection_without_include
             setup_post
-            render jsonapi: [@post]
+            render json: [@post], adapter: :json_api
           end
 
           def render_collection_with_include
             setup_post
-            render jsonapi: [@post], include: 'author, comments'
+            render json: [@post], adapter: :json_api, include: 'author, comments'
           end
         end
 
-        tests LinkedTestController
+        setup do
+          @routes = Rails.application.routes.draw do
+            ActiveSupport::Deprecation.silence do
+              match ':action', :to => LinkedTestController, via: [:get, :post]
+            end
+          end
+        end
 
         def test_render_resource_without_include
-          get :render_resource_without_include
+          get '/render_resource_without_include'
           response = JSON.parse(@response.body)
           refute response.key? 'included'
         end
 
         def test_render_resource_with_include
-          get :render_resource_with_include
+          get '/render_resource_with_include'
           response = JSON.parse(@response.body)
           assert response.key? 'included'
           assert_equal 1, response['included'].size
@@ -102,7 +107,7 @@ def test_render_resource_with_include
         end
 
         def test_render_resource_with_nested_has_many_include
-          get :render_resource_with_nested_has_many_include_wildcard
+          get '/render_resource_with_nested_has_many_include_wildcard'
           response = JSON.parse(@response.body)
           expected_linked = [
             {
@@ -144,7 +149,7 @@ def test_render_resource_with_nested_has_many_include
         end
 
         def test_render_resource_with_include_of_custom_key_by_original
-          get :render_resource_with_include_of_custom_key_by_original
+          get '/render_resource_with_include_of_custom_key_by_original'
           response = JSON.parse(@response.body)
           assert response.key? 'included'
 
@@ -156,33 +161,33 @@ def test_render_resource_with_include_of_custom_key_by_original
         end
 
         def test_render_resource_with_nested_include
-          get :render_resource_with_nested_include
+          get '/render_resource_with_nested_include'
           response = JSON.parse(@response.body)
           assert response.key? 'included'
           assert_equal 3, response['included'].size
         end
 
         def test_render_collection_without_include
-          get :render_collection_without_include
+          get '/render_collection_without_include'
           response = JSON.parse(@response.body)
           refute response.key? 'included'
         end
 
         def test_render_collection_with_include
-          get :render_collection_with_include
+          get '/render_collection_with_include'
           response = JSON.parse(@response.body)
           assert response.key? 'included'
         end
 
         def test_render_resource_with_nested_attributes_even_when_missing_associations
-          get :render_resource_with_missing_nested_has_many_include
+          get '/render_resource_with_missing_nested_has_many_include'
           response = JSON.parse(@response.body)
           assert response.key? 'included'
           refute has_type?(response['included'], 'roles')
         end
 
         def test_render_collection_with_missing_nested_has_many_include
-          get :render_collection_with_missing_nested_has_many_include
+          get '/render_collection_with_missing_nested_has_many_include'
           response = JSON.parse(@response.body)
           assert response.key? 'included'
           assert has_type?(response['included'], 'roles')
diff --git a/test/active_model_serializers/register_jsonapi_renderer_test_isolated.rb b/test/active_model_serializers/register_jsonapi_renderer_test_isolated.rb
new file mode 100644
index 000000000..14e32535f
--- /dev/null
+++ b/test/active_model_serializers/register_jsonapi_renderer_test_isolated.rb
@@ -0,0 +1,143 @@
+require 'support/isolated_unit'
+require 'minitest/mock'
+require 'action_dispatch'
+require 'action_controller'
+
+class JsonApiRendererTest < ActionDispatch::IntegrationTest
+  include ActiveSupport::Testing::Isolation
+
+  class TestController < ActionController::Base
+    class << self
+      attr_accessor :last_request_parameters
+    end
+
+    def render_with_jsonapi_renderer
+      author = Author.new(params[:data][:attributes])
+      render jsonapi: author
+    end
+
+    def parse
+      self.class.last_request_parameters = request.request_parameters
+      head :ok
+    end
+  end
+
+  def teardown
+    TestController.last_request_parameters = nil
+  end
+
+  def assert_parses(expected, actual, headers = {})
+    post '/parse', params: actual, headers: headers
+    assert_response :ok
+    assert_equal(expected, TestController.last_request_parameters)
+  end
+
+  class WithoutRenderer < JsonApiRendererTest
+    setup do
+      require 'rails'
+      require 'active_record'
+      require 'support/rails5_shims'
+      require 'active_model_serializers'
+      require 'fixtures/poro'
+
+      make_basic_app
+
+      Rails.application.routes.draw do
+        ActiveSupport::Deprecation.silence do
+          match ':action', :to => TestController, via: [:get, :post]
+        end
+      end
+    end
+
+    def test_jsonapi_parser_not_registered
+      parsers = if Rails::VERSION::MAJOR >= 5
+                  ActionDispatch::Request.parameter_parsers
+                else
+                  ActionDispatch::ParamsParser::DEFAULT_PARSERS
+                end
+      assert_nil parsers[Mime[:jsonapi]]
+    end
+
+    def test_jsonapi_renderer_not_registered
+      expected = {
+        'data' => {
+          'attributes' => {
+            'name' => 'Johnny Rico'
+          },
+          'type' => 'users'
+        }
+      }
+      payload = '{"data": {"attributes": {"name": "Johnny Rico"}, "type": "authors"}}'
+      headers = { 'CONTENT_TYPE' => 'application/vnd.api+json' }
+      post '/render_with_jsonapi_renderer', params: payload, headers: headers
+      assert expected, response.body
+    end
+
+    def test_jsonapi_parser
+      assert_parses(
+        {},
+        '',
+        'CONTENT_TYPE' => 'application/vnd.api+json'
+      )
+    end
+  end
+
+  class WithRenderer < JsonApiRendererTest
+    setup do
+      require 'rails'
+      require 'active_record'
+      require 'support/rails5_shims'
+      require 'active_model_serializers'
+      require 'fixtures/poro'
+      require 'active_model_serializers/register_jsonapi_renderer'
+
+      make_basic_app
+
+      Rails.application.routes.draw do
+        ActiveSupport::Deprecation.silence do
+          match ':action', :to => TestController, via: [:get, :post]
+        end
+      end
+    end
+
+    def test_jsonapi_parser_registered
+      if Rails::VERSION::MAJOR >= 5
+        parsers = ActionDispatch::Request.parameter_parsers
+        assert_equal Proc, parsers[:jsonapi].class
+      else
+        parsers = ActionDispatch::ParamsParser::DEFAULT_PARSERS
+        assert_equal Proc, parsers[Mime[:jsonapi]].class
+      end
+    end
+
+    def test_jsonapi_renderer_registered
+      expected = {
+        'data' => {
+          'attributes' => {
+            'name' => 'Johnny Rico'
+          },
+          'type' => 'users'
+        }
+      }
+      payload = '{"data": {"attributes": {"name": "Johnny Rico"}, "type": "authors"}}'
+      headers = { 'CONTENT_TYPE' => 'application/vnd.api+json' }
+      post '/render_with_jsonapi_renderer', params: payload, headers: headers
+      assert expected, response.body
+    end
+
+    def test_jsonapi_parser
+      assert_parses(
+        {
+          'data' => {
+            'attributes' => {
+              'name' => 'John Doe'
+            },
+            'type' => 'users'
+          }
+        },
+        '{"data": {"attributes": {"name": "John Doe"}, "type": "users"}}',
+        'CONTENT_TYPE' => 'application/vnd.api+json'
+      )
+    end
+  end
+end
diff --git a/test/support/isolated_unit.rb b/test/support/isolated_unit.rb
index 4adc96a15..d1d18eb69 100644
--- a/test/support/isolated_unit.rb
+++ b/test/support/isolated_unit.rb
@@ -41,6 +41,7 @@
 
 # These files do not require any others and are needed
 # to run the tests
+require 'active_support/testing/autorun'
 require 'active_support/testing/isolation'
 
 module TestHelpers
diff --git a/test/support/rails5_shims.rb b/test/support/rails5_shims.rb
index 0a5fa050d..03a036da6 100644
--- a/test/support/rails5_shims.rb
+++ b/test/support/rails5_shims.rb
@@ -1,7 +1,7 @@
 module Rails5Shims
   module ControllerTests
     # https://github.com/rails/rails/blob/b217354/actionpack/lib/action_controller/test_case.rb
-    REQUEST_KWARGS = [:params, :session, :flash, :method, :body, :xhr].freeze
+    REQUEST_KWARGS = [:params, :headers, :session, :flash, :method, :body, :xhr].freeze
 
     def get(path, *args)
       fold_kwargs!(args)
@@ -30,7 +30,12 @@ def fold_kwargs!(args)
       return unless hash.respond_to?(:key)
       Rails5Shims::ControllerTests::REQUEST_KWARGS.each do |kwarg|
         next unless hash.key?(kwarg)
-        hash.merge! hash.delete(kwarg)
+        value = hash.delete(kwarg)
+        if value.is_a? String
+          args.insert(0, value)
+        else
+          hash.merge! value
+        end
       end
     end
 
@@ -44,4 +49,5 @@ def fold_kwargs!(args)
 end
 if Rails::VERSION::MAJOR < 5
   ActionController::TestCase.send :include, Rails5Shims::ControllerTests
+  ActionDispatch::IntegrationTest.send :include, Rails5Shims::ControllerTests
 end