1 files changed, 6 insertions, 1 deletions
diff --git a/activemodel/lib/active_model/dirty.rb b/activemodel/lib/active_model/dirty.rb
index d3a6bad6bb..57c594f159 100644
--- a/activemodel/lib/active_model/dirty.rb
+++ b/activemodel/lib/active_model/dirty.rb
@@ -86,6 +86,11 @@ module ActiveModel
       attribute_method_affix :prefix => 'reset_', :suffix => '!'
     end
 
+    def initialize(*)
+      @changed_attributes = {}
+      super
+    end
+
     # Do any attributes have unsaved changes?
     #   person.changed? # => false
     #   person.name = 'bob'
@@ -107,7 +112,7 @@ module ActiveModel
     #   person.name = 'bob'
     #   person.changes # => { 'name' => ['bill', 'bob'] }
     def changes
-      changed.inject({}) { |h, attr| h[attr] = attribute_change(attr); h }
+      changed.inject(HashWithIndifferentAccess.new){ |h, attr| h[attr] = attribute_change(attr); h }
     end
 
     # Map of attributes that were changed when the model was saved.