diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index b4d50b7072..7c08f76be1 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -1,5 +1,7 @@
 ## Rails 4.0.0 (unreleased) ##
 
+*   Include mounted_helpers (helpers for accessing mounted engines) in ActionDispatch::IntegrationTest by default. *Piotr Sarnacki*
+
 *   Extracted redirect logic from `ActionController::ForceSSL::ClassMethods.force_ssl`  into `ActionController::ForceSSL#force_ssl_redirect`
 
     *Jeremy Friesen*
diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index e43e897783..25d099d83e 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -1327,7 +1327,7 @@ module ActionDispatch
             msg += @draw_paths.map { |_path| " * #{_path}" }.join("\n")
             raise ArgumentError, msg
           end
-          
+
           route_path = "#{path}/#{name}.rb"
           instance_eval(File.read(route_path), route_path.to_s)
         end
diff --git a/actionpack/lib/action_dispatch/testing/integration.rb b/actionpack/lib/action_dispatch/testing/integration.rb
index 3fdc6688c2..50ca28395b 100644
--- a/actionpack/lib/action_dispatch/testing/integration.rb
+++ b/actionpack/lib/action_dispatch/testing/integration.rb
@@ -193,8 +193,11 @@ module ActionDispatch
 
         # If the app is a Rails app, make url_helpers available on the session
         # This makes app.url_for and app.foo_path available in the console
-        if app.respond_to?(:routes) && app.routes.respond_to?(:url_helpers)
-          singleton_class.class_eval { include app.routes.url_helpers }
+        if app.respond_to?(:routes)
+          singleton_class.class_eval do
+            include app.routes.url_helpers if app.routes.respond_to?(:url_helpers)
+            include app.routes.mounted_helpers if app.routes.respond_to?(:mounted_helpers)
+          end
         end
 
         reset!
diff --git a/actionpack/test/controller/integration_test.rb b/actionpack/test/controller/integration_test.rb
index fb41dcb33a..f18bf33969 100644
--- a/actionpack/test/controller/integration_test.rb
+++ b/actionpack/test/controller/integration_test.rb
@@ -538,11 +538,26 @@ class ApplicationIntegrationTest < ActionDispatch::IntegrationTest
     @routes ||= ActionDispatch::Routing::RouteSet.new
   end
 
+  class MountedApp
+    def self.routes
+      @routes ||= ActionDispatch::Routing::RouteSet.new
+    end
+
+    routes.draw do
+      get 'baz', :to => 'application_integration_test/test#index', :as => :baz
+    end
+
+    def self.call(*)
+    end
+  end
+
   routes.draw do
     get '',    :to => 'application_integration_test/test#index', :as => :empty_string
 
     get 'foo', :to => 'application_integration_test/test#index', :as => :foo
     get 'bar', :to => 'application_integration_test/test#index', :as => :bar
+
+    mount MountedApp => '/mounted', :as => "mounted"
   end
 
   def app
@@ -555,6 +570,10 @@ class ApplicationIntegrationTest < ActionDispatch::IntegrationTest
     assert_equal '/bar', bar_path
   end
 
+  test "includes mounted helpers" do
+    assert_equal '/mounted/baz', mounted.baz_path
+  end
+
   test "route helpers after controller access" do
     get '/'
     assert_equal '/', empty_string_path