diff --git a/actionpack/lib/action_controller/metal/http_authentication.rb b/actionpack/lib/action_controller/metal/http_authentication.rb
index 896238b7dc..e295002b16 100644
--- a/actionpack/lib/action_controller/metal/http_authentication.rb
+++ b/actionpack/lib/action_controller/metal/http_authentication.rb
@@ -228,7 +228,7 @@ module ActionController
       end
 
       def decode_credentials(header)
-        HashWithIndifferentAccess[header.to_s.gsub(/^Digest\s+/,'').split(',').map do |pair|
+        ActiveSupport::HashWithIndifferentAccess[header.to_s.gsub(/^Digest\s+/, '').split(',').map do |pair|
           key, value = pair.split('=', 2)
           [key.strip, value.to_s.gsub(/^"|"$/,'').delete('\'')]
         end]
diff --git a/actionpack/lib/action_dispatch/http/parameters.rb b/actionpack/lib/action_dispatch/http/parameters.rb
index 6610315da7..25edd196c3 100644
--- a/actionpack/lib/action_dispatch/http/parameters.rb
+++ b/actionpack/lib/action_dispatch/http/parameters.rb
@@ -72,7 +72,7 @@ module ActionDispatch
         end
       end
 
-      # Convert nested Hash to HashWithIndifferentAccess
+      # Convert nested Hash to ActiveSupport::HashWithIndifferentAccess
       def normalize_parameters(value)
         case value
         when Hash
diff --git a/actionpack/lib/action_dispatch/http/upload.rb b/actionpack/lib/action_dispatch/http/upload.rb
index f9b007b57b..8a97248eb3 100644
--- a/actionpack/lib/action_dispatch/http/upload.rb
+++ b/actionpack/lib/action_dispatch/http/upload.rb
@@ -75,7 +75,7 @@ module ActionDispatch
     end
 
     module Upload # :nodoc:
-      # Convert nested Hash to HashWithIndifferentAccess and replace
+      # Convert nested Hash to ActiveSupport::HashWithIndifferentAccess and replace
       # file upload hash with UploadedFile objects
       def normalize_parameters(value)
         if Hash === value && value.has_key?(:tempfile)
diff --git a/actionpack/test/controller/url_for_test.rb b/actionpack/test/controller/url_for_test.rb
index d3fc7128e9..ba24e7fac5 100644
--- a/actionpack/test/controller/url_for_test.rb
+++ b/actionpack/test/controller/url_for_test.rb
@@ -2,7 +2,6 @@ require 'abstract_unit'
 
 module AbstractController
   module Testing
-
     class UrlForTest < ActionController::TestCase
       class W
         include ActionDispatch::Routing::RouteSet.new.tap { |r| r.draw { get ':controller(/:action(/:id(.:format)))' } }.url_helpers
@@ -350,10 +349,10 @@ module AbstractController
       def test_with_hash_with_indifferent_access
         W.default_url_options[:controller] = 'd'
         W.default_url_options[:only_path]  = false
-        assert_equal("/c", W.new.url_for(HashWithIndifferentAccess.new('controller' => 'c', 'only_path' => true)))
+        assert_equal("/c", W.new.url_for(ActiveSupport::HashWithIndifferentAccess.new('controller' => 'c', 'only_path' => true)))
 
         W.default_url_options[:action] = 'b'
-        assert_equal("/c/a", W.new.url_for(HashWithIndifferentAccess.new('controller' => 'c', 'action' => 'a', 'only_path' => true)))
+        assert_equal("/c/a", W.new.url_for(ActiveSupport::HashWithIndifferentAccess.new('controller' => 'c', 'action' => 'a', 'only_path' => true)))
       end
 
       def test_url_params_with_nil_to_param_are_not_in_url
diff --git a/activemodel/lib/active_model/dirty.rb b/activemodel/lib/active_model/dirty.rb
index ecb7a9e9b1..6e67cd2285 100644
--- a/activemodel/lib/active_model/dirty.rb
+++ b/activemodel/lib/active_model/dirty.rb
@@ -119,7 +119,7 @@ module ActiveModel
     #   person.name = 'bob'
     #   person.changes # => { "name" => ["bill", "bob"] }
     def changes
-      HashWithIndifferentAccess[changed.map { |attr| [attr, attribute_change(attr)] }]
+      ActiveSupport::HashWithIndifferentAccess[changed.map { |attr| [attr, attribute_change(attr)] }]
     end
 
     # Returns a hash of attributes that were changed before the model was saved.
diff --git a/activerecord/lib/active_record/store.rb b/activerecord/lib/active_record/store.rb
index df7f58c81f..cf4cf9e602 100644
--- a/activerecord/lib/active_record/store.rb
+++ b/activerecord/lib/active_record/store.rb
@@ -107,7 +107,7 @@ module ActiveRecord
     private
       def initialize_store_attribute(store_attribute)
         attribute = send(store_attribute)
-        unless attribute.is_a?(HashWithIndifferentAccess)
+        unless attribute.is_a?(ActiveSupport::HashWithIndifferentAccess)
           attribute = IndifferentCoder.as_indifferent_hash(attribute)
           send :"#{store_attribute}=", attribute
         end
@@ -134,12 +134,12 @@ module ActiveRecord
 
       def self.as_indifferent_hash(obj)
         case obj
-        when HashWithIndifferentAccess
+        when ActiveSupport::HashWithIndifferentAccess
           obj
         when Hash
           obj.with_indifferent_access
         else
-          HashWithIndifferentAccess.new
+          ActiveSupport::HashWithIndifferentAccess.new
         end
       end
     end
diff --git a/activerecord/test/cases/nested_attributes_test.rb b/activerecord/test/cases/nested_attributes_test.rb
index 9574678e38..94837341fc 100644
--- a/activerecord/test/cases/nested_attributes_test.rb
+++ b/activerecord/test/cases/nested_attributes_test.rb
@@ -311,7 +311,7 @@ class TestNestedAttributesOnAHasOneAssociation < ActiveRecord::TestCase
   end
 
   def test_should_also_work_with_a_HashWithIndifferentAccess
-    @pirate.ship_attributes = HashWithIndifferentAccess.new(:id => @ship.id, :name => 'Davy Jones Gold Dagger')
+    @pirate.ship_attributes = ActiveSupport::HashWithIndifferentAccess.new(:id => @ship.id, :name => 'Davy Jones Gold Dagger')
 
     assert @pirate.ship.persisted?
     assert_equal 'Davy Jones Gold Dagger', @pirate.ship.name
@@ -593,7 +593,7 @@ module NestedAttributesOnACollectionAssociationTests
   end
 
   def test_should_also_work_with_a_HashWithIndifferentAccess
-    @pirate.send(association_setter, HashWithIndifferentAccess.new('foo' => HashWithIndifferentAccess.new(:id => @child_1.id, :name => 'Grace OMalley')))
+    @pirate.send(association_setter, ActiveSupport::HashWithIndifferentAccess.new('foo' => ActiveSupport::HashWithIndifferentAccess.new(:id => @child_1.id, :name => 'Grace OMalley')))
     @pirate.save
     assert_equal 'Grace OMalley', @child_1.reload.name
   end
diff --git a/activerecord/test/cases/store_test.rb b/activerecord/test/cases/store_test.rb
index 562ca8d9ff..43bf285ba9 100644
--- a/activerecord/test/cases/store_test.rb
+++ b/activerecord/test/cases/store_test.rb
@@ -67,9 +67,9 @@ class StoreTest < ActiveRecord::TestCase
   end
 
   test "preserve store attributes data in HashWithIndifferentAccess format without any conversion" do
-    @john.json_data = HashWithIndifferentAccess.new(:height => 'tall', 'weight' => 'heavy')
+    @john.json_data = ActiveSupport::HashWithIndifferentAccess.new(:height => 'tall', 'weight' => 'heavy')
     @john.height = 'low'
-    assert_equal true, @john.json_data.instance_of?(HashWithIndifferentAccess)
+    assert_equal true, @john.json_data.instance_of?(ActiveSupport::HashWithIndifferentAccess)
     assert_equal 'low', @john.json_data[:height]
     assert_equal 'low', @john.json_data['height']
     assert_equal 'heavy', @john.json_data[:weight]
@@ -95,7 +95,7 @@ class StoreTest < ActiveRecord::TestCase
   test "convert store attributes from any format other than Hash or HashWithIndifferent access losing the data" do
     @john.json_data = "somedata"
     @john.height = 'low'
-    assert_equal true, @john.json_data.instance_of?(HashWithIndifferentAccess)
+    assert_equal true, @john.json_data.instance_of?(ActiveSupport::HashWithIndifferentAccess)
     assert_equal 'low', @john.json_data[:height]
     assert_equal 'low', @john.json_data['height']
     assert_equal false, @john.json_data.delete_if { |k, v| k == 'height' }.any?
@@ -143,5 +143,4 @@ class StoreTest < ActiveRecord::TestCase
     assert_raise(NoMethodError) { @john.stored_attributes = Hash.new }
     assert_raise(NoMethodError) { @john.stored_attributes }
   end
-
 end
diff --git a/activesupport/test/core_ext/hash_ext_test.rb b/activesupport/test/core_ext/hash_ext_test.rb
index 5fc81ba6fc..84dd9bc983 100644
--- a/activesupport/test/core_ext/hash_ext_test.rb
+++ b/activesupport/test/core_ext/hash_ext_test.rb
@@ -8,7 +8,7 @@ require 'active_support/core_ext/object/deep_dup'
 require 'active_support/inflections'
 
 class HashExtTest < ActiveSupport::TestCase
-  class IndifferentHash < HashWithIndifferentAccess
+  class IndifferentHash < ActiveSupport::HashWithIndifferentAccess
   end
 
   class SubclassingArray < Array
diff --git a/guides/source/action_controller_overview.md b/guides/source/action_controller_overview.md
index 46ff9027fd..f06aeccffc 100644
--- a/guides/source/action_controller_overview.md
+++ b/guides/source/action_controller_overview.md
@@ -114,7 +114,7 @@ To send a hash you include the key name inside the brackets:
 
 When this form is submitted, the value of `params[:client]` will be `{"name" => "Acme", "phone" => "12345", "address" => {"postcode" => "12345", "city" => "Carrot City"}}`. Note the nested hash in `params[:client][:address]`.
 
-Note that the `params` hash is actually an instance of `HashWithIndifferentAccess` from Active Support, which acts like a hash that lets you use symbols and strings interchangeably as keys.
+Note that the `params` hash is actually an instance of `ActiveSupport::HashWithIndifferentAccess`, which acts like a hash that lets you use symbols and strings interchangeably as keys.
 
 ### JSON/XML parameters
 
diff --git a/guides/source/getting_started.md b/guides/source/getting_started.md
index aa841d5867..0542cbf514 100644
--- a/guides/source/getting_started.md
+++ b/guides/source/getting_started.md
@@ -417,7 +417,7 @@ def create
 end
 ```
 
-The `render` method here is taking a very simple hash with a key of `text` and value of `params[:post].inspect`. The `params` method is the object which represents the parameters (or fields) coming in from the form. The `params` method returns a `HashWithIndifferentAccess` object, which allows you to access the keys of the hash using either strings or symbols. In this situation, the only parameters that matter are the ones from the form.
+The `render` method here is taking a very simple hash with a key of `text` and value of `params[:post].inspect`. The `params` method is the object which represents the parameters (or fields) coming in from the form. The `params` method returns an `ActiveSupport::HashWithIndifferentAccess` object, which allows you to access the keys of the hash using either strings or symbols. In this situation, the only parameters that matter are the ones from the form.
 
 If you re-submit the form one more time you'll now no longer get the missing template error. Instead, you'll see something that looks like the following: