diff --git a/lib/will_paginate.rb b/lib/will_paginate.rb
index 889718e76..5821d3469 100644
--- a/lib/will_paginate.rb
+++ b/lib/will_paginate.rb
@@ -2,8 +2,10 @@
 module WillPaginate
 end
 
-if defined?(::Rails::Railtie)
+if defined?(Rails::Railtie)
   require 'will_paginate/railtie'
+elsif defined?(Rails::Initializer)
+  raise "will_paginate 3.0 is not compatible with Rails 2.3 or older"
 end
 
 if defined?(Merb::AbstractController)