diff --git a/has_enum.gemspec b/has_enum.gemspec
index 863747e..8ced5b4 100644
--- a/has_enum.gemspec
+++ b/has_enum.gemspec
@@ -23,3 +23,4 @@ Gem::Specification.new do |s|
   s.executables      = `git ls-files -- bin/*`.split("\n").map{ |f| File.basename(f) }
   s.require_paths    = ["lib"]
 end
+
diff --git a/lib/has_enum.rb b/lib/has_enum.rb
index f946829..6764ed1 100644
--- a/lib/has_enum.rb
+++ b/lib/has_enum.rb
@@ -3,9 +3,6 @@ module HasEnum
   autoload :ClassMethods,            'has_enum/class_methods'
 
   def self.included(base)
-    base.class_attribute :enums
-    base.enums ||= HashWithIndifferentAccess.new
-
     base.extend ClassMethods
   end
 
diff --git a/lib/has_enum/class_methods.rb b/lib/has_enum/class_methods.rb
index 7cc03a4..21fcbaa 100644
--- a/lib/has_enum/class_methods.rb
+++ b/lib/has_enum/class_methods.rb
@@ -1,10 +1,12 @@
 module HasEnum::ClassMethods
 
   def enum_values(attribute)
+  	return nil unless defined?(enums)
     enums[attribute]
   end
 
   def has_enum?(enum)
+  	return false unless defined?(enums)
     enums.include? enum
   end
 
@@ -25,6 +27,13 @@ def has_enums
   end
 
   def has_enum(*params)
+	self.class_eval do
+		unless defined?(self.enums)
+			self.class_attribute :enums
+		end
+		self.enums ||= HashWithIndifferentAccess.new
+	end
+
     options = params.extract_options!
     options.assert_valid_keys(:query_methods, :scopes, :presence, :multiple, :validates)