4 files changed, 6 insertions, 1 deletions
diff --git a/activemodel/lib/active_model/dirty.rb b/activemodel/lib/active_model/dirty.rb
index cb67ef7270..2d5acdfced 100644
--- a/activemodel/lib/active_model/dirty.rb
+++ b/activemodel/lib/active_model/dirty.rb
@@ -1,4 +1,7 @@
+require 'active_model/attribute_methods'
+require 'active_support/concern'
 require 'active_support/hash_with_indifferent_access'
+require 'active_support/core_ext/object/duplicable'
 
 module ActiveModel
   # <tt>ActiveModel::Dirty</tt> provides a way to track changes in your
diff --git a/activemodel/lib/active_model/errors.rb b/activemodel/lib/active_model/errors.rb
index a9a54a90e0..8d28040c32 100644
--- a/activemodel/lib/active_model/errors.rb
+++ b/activemodel/lib/active_model/errors.rb
@@ -1,5 +1,6 @@
 require 'active_support/core_ext/array/wrap'
 require 'active_support/core_ext/string/inflections'
+require 'active_support/core_ext/object/blank'
 require 'active_support/ordered_hash'
 
 module ActiveModel
diff --git a/activemodel/lib/active_model/validations/inclusion.rb b/activemodel/lib/active_model/validations/inclusion.rb
index 0c1334fe1b..c1838bb93e 100644
--- a/activemodel/lib/active_model/validations/inclusion.rb
+++ b/activemodel/lib/active_model/validations/inclusion.rb
@@ -4,7 +4,7 @@ module ActiveModel
       def check_validity!
          raise ArgumentError, "An object with the method include? is required must be supplied as the " <<
                               ":in option of the configuration hash" unless options[:in].respond_to?(:include?)
-       end
+      end
 
       def validate_each(record, attribute, value)
         return if options[:in].include?(value)
diff --git a/activemodel/lib/active_model/validator.rb b/activemodel/lib/active_model/validator.rb
index b7c52be3f0..906d239bcc 100644
--- a/activemodel/lib/active_model/validator.rb
+++ b/activemodel/lib/active_model/validator.rb
@@ -1,5 +1,6 @@
 require 'active_support/core_ext/array/wrap'
 require "active_support/core_ext/module/anonymous"
+require 'active_support/core_ext/object/blank'
 
 module ActiveModel #:nodoc:
   # A simple base class that can be used along with