canard.gemspec in canard-0.4.1 vs canard.gemspec in canard-0.4.2.pre

@@ -1,8 +1,9 @@
 # -*- encoding: utf-8 -*-
 $:.push File.expand_path("../lib", __FILE__)
 require "canard/version"
+require 'rails'
 
 Gem::Specification.new do |s|
   s.name        = "canard"
   s.version     = Canard::VERSION
   s.date        = `git log -1 --format="%cd" --date=short lib/canard/version.rb`
@@ -26,8 +27,13 @@
     s.add_development_dependency "mongoid", "~> 2.0"
   else
     s.add_development_dependency "mongoid", "~> 3.0"
   end
 
-  s.add_runtime_dependency "cancan"
+  s.requirements << 'cancan for Rails3 and earlier or the Rails4 compatible cancancan fork.'
+  if Rails.version > '3'
+    s.add_runtime_dependency "cancancan"
+  else
+    s.add_runtime_dependency "cancan"
+  end
   s.add_runtime_dependency "role_model"
 end