diff --git a/README.md b/README.md
index e855cc15..8c9b5529 100644
--- a/README.md
+++ b/README.md
@@ -15,6 +15,14 @@ ActiveHash also ships with:
   * ActiveFile: a base class that you can use to create file data sources
   * ActiveYaml: a base class that will turn YAML into a hash and load the data into an ActiveHash object
 
+## !!! Important notice !!!
+We have changed returned value to chainable by v3.0.0. It's not just an `Array` instance anymore.
+If it breaks your application, please report us on [issues](https://github.com/zilkey/active_hash/issues), and use v2.x.x as following..
+
+```ruby
+gem 'active_hash', '~> 2.3.0'
+```
+
 ## Installation
 
 Bundler: