diff --git a/activesupport/lib/active_support/hash_with_indifferent_access.rb b/activesupport/lib/active_support/hash_with_indifferent_access.rb
index c406dd3c2e732f6091046c550d6160be447bfdff..06dd18966e0173e2fe67985e91bbcab304677e2f 100644
--- a/activesupport/lib/active_support/hash_with_indifferent_access.rb
+++ b/activesupport/lib/active_support/hash_with_indifferent_access.rb
@@ -28,7 +28,7 @@ def default(key = nil)
     end
 
     def self.new_from_hash_copying_default(hash)
-      ActiveSupport::HashWithIndifferentAccess.new(hash).tap do |new_hash|
+      new(hash).tap do |new_hash|
         new_hash.default = hash.default
       end
     end
@@ -97,7 +97,9 @@ def values_at(*indices)
 
     # Returns an exact copy of the hash.
     def dup
-      HashWithIndifferentAccess.new(self)
+      self.class.new(self).tap do |new_hash|
+        new_hash.default = default
+      end
     end
 
     # Merges the instantized and the specified hashes together, giving precedence to the values from the second hash
diff --git a/activesupport/test/core_ext/hash_ext_test.rb b/activesupport/test/core_ext/hash_ext_test.rb
index cdf27ba35ade76ec0088b5c03934a6af8fbbfc78..03fbee93a2d4a47dff97de7bb8e84844c0f1fd0e 100644
--- a/activesupport/test/core_ext/hash_ext_test.rb
+++ b/activesupport/test/core_ext/hash_ext_test.rb
@@ -6,6 +6,9 @@
 require 'active_support/core_ext/object/conversions'
 
 class HashExtTest < Test::Unit::TestCase
+  class IndifferentHash < HashWithIndifferentAccess
+  end
+
   def setup
     @strings = { 'a' => 1, 'b' => 2 }
     @symbols = { :a  => 1, :b  => 2 }
@@ -267,7 +270,6 @@ def test_to_options_on_indifferent_preserves_hash
     assert_equal 1, h['first']
   end
 
-
   def test_indifferent_subhashes
     h = {'user' => {'id' => 5}}.with_indifferent_access
     ['user', :user].each {|user| [:id, 'id'].each {|id| assert_equal 5, h[user][id], "h[#{user.inspect}][#{id.inspect}] should be 5"}}
@@ -276,6 +278,17 @@ def test_indifferent_subhashes
     ['user', :user].each {|user| [:id, 'id'].each {|id| assert_equal 5, h[user][id], "h[#{user.inspect}][#{id.inspect}] should be 5"}}
   end
 
+  def test_indifferent_duplication
+    # Should preserve default value
+    h = HashWithIndifferentAccess.new
+    h.default = '1234'
+    assert_equal h.default, h.dup.default
+
+    # Should preserve class for subclasses
+    h = IndifferentHash.new
+    assert_equal h.class, h.dup.class
+  end
+
   def test_assert_valid_keys
     assert_nothing_raised do
       { :failure => "stuff", :funny => "business" }.assert_valid_keys([ :failure, :funny ])