diff --git a/lib/paperclip/attachment.rb b/lib/paperclip/attachment.rb
index 9c93ea2..5efb267 100644
--- a/lib/paperclip/attachment.rb
+++ b/lib/paperclip/attachment.rb
@@ -1,6 +1,8 @@
 require 'fastimage'
 
 require 'paperclip/styles_parser'
+require 'active_support/core_ext/module/delegation'
+require 'active_support/core_ext/string/inflections'
 
 module Paperclip
   # The Attachment class manages the files for a given attachment. It saves
diff --git a/lib/paperclip/callback_compatability.rb b/lib/paperclip/callback_compatability.rb
index 1e437d7..dd550c7 100644
--- a/lib/paperclip/callback_compatability.rb
+++ b/lib/paperclip/callback_compatability.rb
@@ -1,3 +1,5 @@
+require 'active_support/version'
+
 module Paperclip
   module CallbackCompatability
     module_function
@@ -33,7 +35,7 @@ module Paperclip
     module Rails3
       module Defining
         TERMINATOR =
-          if Gem::Version.new(ActiveRecord::VERSION::STRING) >= Gem::Version.new('4.1')
+          if Gem::Version.new(ActiveSupport::VERSION::STRING) >= Gem::Version.new('4.1')
             ->(target, result) { result == false }
           else
             'result == false'