diff --git a/lib/identity_cache.rb b/lib/identity_cache.rb
index <HASH>..<HASH> 100644
--- a/lib/identity_cache.rb
+++ b/lib/identity_cache.rb
@@ -1,4 +1,5 @@
 require 'active_record'
+require 'active_support/core_ext/module/attribute_accessors'
 require 'ar_transaction_changes'
 
 require "identity_cache/version"
Add require to AS attribute_accessors

ActiveSupport 4+ doesnt require that by default, so we need to include it.