diff --git a/.travis.yml b/.travis.yml
index 59d4585..a1dfbfd 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,6 +5,9 @@ rvm:
   - "2.0"
   - "2.1"
   - "2.2"
+  - "2.3"
+  - "2.4"
+  - "2.5"
 env:
   - RAILS_VERSION=""
   - RAILS_VERSION="~>3.2.0"
@@ -13,6 +16,9 @@ env:
   - RAILS_VERSION="~>4.0.0"
   - RAILS_VERSION="~>4.1.0"
   - RAILS_VERSION="~>4.2.0"
+  - RAILS_VERSION="~>5.0.0"
+  - RAILS_VERSION="~>5.1.0"
+  - RAILS_VERSION="~>5.2.0"
   - RAILS_VERSION="" MONETA_VERSION="~> 0.6.0"
   - RAILS_VERSION="" MONETA_VERSION="~> 0.7.0"
 notifications:
diff --git a/lib/rocket_pants/base.rb b/lib/rocket_pants/base.rb
index f64784d..f5becdc 100644
--- a/lib/rocket_pants/base.rb
+++ b/lib/rocket_pants/base.rb
@@ -15,11 +15,9 @@ class Base < ActionController::Metal
     end
 
     MODULES = [
-      ActionController::HideActions,
       ActionController::UrlFor,
       ActionController::Redirecting,
       ActionController::ConditionalGet,
-      ActionController::RackDelegation,
       record_identifier_klass,
       ActionController::HttpAuthentication::Basic::ControllerMethods,
       ActionController::HttpAuthentication::Digest::ControllerMethods,
diff --git a/lib/rocket_pants/controller/format_verification.rb b/lib/rocket_pants/controller/format_verification.rb
index 84f50ea..c020d2c 100644
--- a/lib/rocket_pants/controller/format_verification.rb
+++ b/lib/rocket_pants/controller/format_verification.rb
@@ -3,7 +3,7 @@ module FormatVerification
     extend ActiveSupport::Concern
 
     included do
-      before_filter :ensure_has_valid_format
+      before_action :ensure_has_valid_format
     end
 
     private
@@ -13,4 +13,4 @@ def ensure_has_valid_format
     end
 
   end
-end
\ No newline at end of file
+end
diff --git a/lib/rocket_pants/controller/jsonp.rb b/lib/rocket_pants/controller/jsonp.rb
index 0459ca8..fe74cdc 100644
--- a/lib/rocket_pants/controller/jsonp.rb
+++ b/lib/rocket_pants/controller/jsonp.rb
@@ -43,8 +43,8 @@ def wrap_response_in_jsonp
       # Finally, set up the callback using the JSONP parameter.
       response.content_type     = 'application/javascript'
       response.body             = "#{jsonp_parameter}(#{response.body});"
-      headers['Content-Length'] = Rack::Utils.bytesize(response.body).to_s
+      headers['Content-Length'] = (response.body.bytesize).to_s
     end
 
   end
-end
\ No newline at end of file
+end
diff --git a/lib/rocket_pants/controller/rescuable.rb b/lib/rocket_pants/controller/rescuable.rb
index 1c9d9ac..d04562e 100644
--- a/lib/rocket_pants/controller/rescuable.rb
+++ b/lib/rocket_pants/controller/rescuable.rb
@@ -23,7 +23,13 @@ module Rescuable
         end
       },
       :bugsnag => lambda { |controller, exception, request|
-        controller.send(:notify_bugsnag, exception, request: request)
+        if controller.respond_to?(:notify_bugsnag, true)
+          controller.send(:notify_bugsnag, exception, request: request)
+        else
+          # Bugsnag v6 removed #notify_bugsnag controller method
+          # Use #notify directly
+          Bugsnag.notify(exception)
+        end
       }
     }
 
diff --git a/lib/rocket_pants/controller/respondable.rb b/lib/rocket_pants/controller/respondable.rb
index 6b6476e..c203a61 100644
--- a/lib/rocket_pants/controller/respondable.rb
+++ b/lib/rocket_pants/controller/respondable.rb
@@ -123,9 +123,9 @@ def render_json(json, options = {})
       json = encode_to_json(json) unless json.respond_to?(:to_str)
       # Encode the object to json.
       self.status        ||= :ok
-      self.content_type  ||= Mime::JSON
+      self.content_type  ||= Mime[:json]
       self.response_body   = json
-      headers['Content-Length'] = Rack::Utils.bytesize(json).to_s
+      headers['Content-Length'] = (json.bytesize).to_s
     end
 
     # Renders a raw object, without any wrapping etc.
@@ -227,4 +227,4 @@ def metadata_for(object, options, type, singular)
     end
 
   end
-end
\ No newline at end of file
+end
diff --git a/lib/rocket_pants/controller/versioning.rb b/lib/rocket_pants/controller/versioning.rb
index 24eeff6..fa5bfb6 100644
--- a/lib/rocket_pants/controller/versioning.rb
+++ b/lib/rocket_pants/controller/versioning.rb
@@ -12,7 +12,7 @@ module ClassMethods
       def version(version)
         version = version..version if version.is_a?(Integer)
         self._version_range = version
-        before_filter :verify_api_version
+        before_action :verify_api_version
       end
 
     end
diff --git a/lib/rocket_pants/railtie.rb b/lib/rocket_pants/railtie.rb
index 9cb91fa..0fcee75 100644
--- a/lib/rocket_pants/railtie.rb
+++ b/lib/rocket_pants/railtie.rb
@@ -7,7 +7,7 @@ class Railtie < Rails::Railtie
     config.rocket_pants.pass_through_errors = nil
     config.rocket_pants.pass_through_errors = nil
 
-    config.i18n.railties_load_path << File.expand_path('../locale/en.yml', __FILE__)
+    config.i18n.load_path << File.expand_path('../locale/en.yml', __FILE__)
 
     initializer "rocket_pants.logger" do
       ActiveSupport.on_load(:rocket_pants) { self.logger ||= Rails.logger }
@@ -39,7 +39,12 @@ class Railtie < Rails::Railtie
 
     initializer "rocket_pants.setup_caching" do |app|
       if RocketPants.caching_enabled?
-        app.middleware.insert 'Rack::Runtime', RocketPants::CacheMiddleware
+        run_time_middleware = if Rails::VERSION::MAJOR >= 5
+          Rack::Runtime
+        else
+          "Rack::Runtime"
+        end
+        app.middleware.insert run_time_middleware, RocketPants::CacheMiddleware
       end
     end
 
@@ -54,4 +59,4 @@ class Railtie < Rails::Railtie
     end
 
   end
-end
\ No newline at end of file
+end
diff --git a/lib/rocket_pants/test_helper.rb b/lib/rocket_pants/test_helper.rb
index 1ecb6eb..06bf963 100644
--- a/lib/rocket_pants/test_helper.rb
+++ b/lib/rocket_pants/test_helper.rb
@@ -9,9 +9,6 @@ module TestHelper
 
       # Extend the response on first include.
       class_attribute :_default_version
-      unless ActionController::TestResponse < ResponseHelper
-        ActionController::TestResponse.send :include, ResponseHelper
-      end
 
       unless ActionDispatch::TestResponse < ResponseHelper
         ActionDispatch::TestResponse.send :include, ResponseHelper
@@ -90,21 +87,30 @@ def insert_action_controller_testing_into_base
 
     # Like process, but automatically adds the api version.
     def process(action, *args)
-
       insert_action_controller_testing_into_base
 
-      # Rails 4 changes the method signature. In rails 3, parameters is the first argument.
-      # In Rails 4, it's the second.
-      if args.first.is_a?(String)
-        parameters = (args[1] ||= {})
+      if Rails::VERSION::MAJOR <= 4
+        # Rails 4 changes the method signature. In rails 3, parameters is the first argument.
+        # In Rails 4, it's the second.
+        if args.first.is_a?(String)
+          parameters = (args[1] ||= {})
+        else
+          parameters = (args[0] ||= {})
+        end
       else
         parameters = (args[0] ||= {})
       end
 
       response.recycle_cached_body!
 
-      if _default_version.present? && parameters[:version].blank? && parameters['version'].blank?
-        parameters[:version] = _default_version
+      if Rails::VERSION::MAJOR <= 4
+        if _default_version.present? && parameters[:version].blank? && parameters['version'].blank?
+          parameters[:version] = _default_version
+        end
+      else
+        if _default_version.present? && parameters[:params][:version].blank?
+          parameters[:params][:version] = _default_version
+        end
       end
 
       super action, *args
diff --git a/rocket_pants.gemspec b/rocket_pants.gemspec
index 302529a..edbc764 100644
--- a/rocket_pants.gemspec
+++ b/rocket_pants.gemspec
@@ -13,21 +13,21 @@ Gem::Specification.new do |s|
   s.description = "Rocket Pants adds JSON API love to Rails and ActionController, making it simpler to build API-oriented controllers."
   s.required_rubygems_version = ">= 1.3.6"
 
-  s.add_dependency 'actionpack', '>= 3.0', '< 5.0'
-  s.add_dependency 'railties',   '>= 3.0', '< 5.0'
+  s.add_dependency 'actionpack', '>= 3.0', '< 6.0'
+  s.add_dependency 'railties',   '>= 3.0', '< 6.0'
   s.add_dependency 'will_paginate', '~> 3.0'
-  s.add_dependency 'hashie',        '>= 1.0', '< 3'
+  s.add_dependency 'hashie',        '>= 1.0', '< 4'
   s.add_dependency 'api_smith'
   s.add_dependency 'moneta'
   s.add_development_dependency 'rspec',       '>= 2.4', '< 4.0'
   s.add_development_dependency 'rspec-rails', '>= 2.4', '< 4.0'
   s.add_development_dependency 'rr',          '~> 1.0'
   s.add_development_dependency 'webmock'
-  s.add_development_dependency 'activerecord', '>= 3.0', '< 5.0'
+  s.add_development_dependency 'activerecord', '>= 3.0', '< 6.0'
   s.add_development_dependency 'sqlite3'
   s.add_development_dependency 'reversible_data', '~> 1.0'
   s.add_development_dependency 'kaminari'
 
   s.files        = Dir.glob("{lib}/**/*")
   s.require_path = 'lib'
-end
\ No newline at end of file
+end
diff --git a/spec/rocket_pants/controller/error_handling_spec.rb b/spec/rocket_pants/controller/error_handling_spec.rb
index 9563650..8d23c64 100644
--- a/spec/rocket_pants/controller/error_handling_spec.rb
+++ b/spec/rocket_pants/controller/error_handling_spec.rb
@@ -75,6 +75,9 @@
           before :each do
             controller_class.use_named_exception_notifier :bugsnag
             stub.instance_of(controller_class).notify_bugsnag {}
+            Bugsnag = Class.new do	
+              define_singleton_method(:notify) { |exception| }	
+            end
           end
 
           it 'should send notification when it is the named exception notifier' do
diff --git a/spec/rocket_pants/controller_spec.rb b/spec/rocket_pants/controller_spec.rb
index b6cd677..a15a8f2 100644
--- a/spec/rocket_pants/controller_spec.rb
+++ b/spec/rocket_pants/controller_spec.rb
@@ -410,7 +410,7 @@ def object.serializable_hash(*); {:serialised => true}; end
       get :echo, :echo => "Hello World", :callback => "test"
       response.content_type.should include 'application/javascript'
       response.body.should == %|test({"response":{"echo":"Hello World"}});|
-      response.headers['Content-Length'].to_i.should == Rack::Utils.bytesize(response.body)
+      response.headers['Content-Length'].to_i.should == response.body.bytesize
     end
 
   end
@@ -436,4 +436,4 @@ def object.serializable_hash(*); {:serialised => true}; end
 
   end
 
-end
\ No newline at end of file
+end