diff --git a/actionpack/CHANGELOG b/actionpack/CHANGELOG
index 49fd59c72e..7d4978f751 100644
--- a/actionpack/CHANGELOG
+++ b/actionpack/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* CHANGED DEFAILT: File-based sessions now have a suffix of ".rails_session" instead of a prefix called "ruby_sess." [DHH]
+
 * Fixed Effect.Appear in effects.js to work with floats in Safari #3524, #3813, #3044 [Thomas Fuchs]
 
 * Fixed that default image extension was not appended when using a full URL with AssetTagHelper#image_tag #4032, #3728 [rubyonrails@beautifulpixel.com]
diff --git a/actionpack/lib/action_controller/cgi_process.rb b/actionpack/lib/action_controller/cgi_process.rb
index b22921ce8b..f30481ee8a 100644
--- a/actionpack/lib/action_controller/cgi_process.rb
+++ b/actionpack/lib/action_controller/cgi_process.rb
@@ -36,8 +36,8 @@ module ActionController #:nodoc:
 
     DEFAULT_SESSION_OPTIONS = {
       :database_manager => CGI::Session::PStore,
-      :prefix => "ruby_sess.",
-      :session_path => "/"
+      :suffix           => ".rails_session",
+      :session_path     => "/"
     } unless const_defined?(:DEFAULT_SESSION_OPTIONS)
 
     def initialize(cgi, session_options = {})