diff --git a/lib/devise/mapping.rb b/lib/devise/mapping.rb
index 58cd3903..6e654c18 100644
--- a/lib/devise/mapping.rb
+++ b/lib/devise/mapping.rb
@@ -77,7 +77,7 @@ module Devise
 
     # Return modules for the mapping.
     def modules
-      @modules ||= to.devise_modules
+      @modules ||= to.respond_to?(:devise_modules) ? to.devise_modules : []
     end
 
     # Gives the class the mapping points to.
diff --git a/lib/devise/models.rb b/lib/devise/models.rb
index 7d02244e..51438f64 100644
--- a/lib/devise/models.rb
+++ b/lib/devise/models.rb
@@ -45,7 +45,6 @@ module Devise
     # for a complete description on those values.
     #
     def devise(*modules)
-      define_devise_class_attributes!
       include Devise::Models::Authenticatable
       options = modules.extract_options!
 
@@ -75,32 +74,6 @@ module Devise
     def devise_modules_hook!
       yield
     end
-
-    # Find an initialize a record setting an error if it can't be found.
-    def find_or_initialize_with_error_by(attribute, value, error=:invalid) #:nodoc:
-      if value.present?
-        conditions = { attribute => value }
-        record = find(:first, :conditions => conditions)
-      end
-
-      unless record
-        record = new
-        if value.present?
-          record.send(:"#{attribute}=", value)
-        else
-          error = :blank
-        end
-        record.errors.add(attribute, error)
-      end
-
-      record
-    end
-
-    def define_devise_class_attributes! #:nodoc:
-      return if respond_to?(:devise_modules)
-      class_attribute :devise_modules, :instance_writer => false
-      self.devise_modules = []
-    end
   end
 end
 
diff --git a/lib/devise/models/authenticatable.rb b/lib/devise/models/authenticatable.rb
index 3c9a18e2..15182171 100644
--- a/lib/devise/models/authenticatable.rb
+++ b/lib/devise/models/authenticatable.rb
@@ -39,6 +39,11 @@ module Devise
     module Authenticatable
       extend ActiveSupport::Concern
 
+      included do
+        class_attribute :devise_modules, :instance_writer => false
+        self.devise_modules ||= []
+      end
+
       # Check if the current object is valid for authentication. This method and find_for_authentication
       # are the methods used in a Warden::Strategy to check if a model should be signed in or not.
       #
@@ -86,6 +91,26 @@ module Devise
         def find_for_authentication(conditions)
           find(:first, :conditions => conditions)
         end
+
+        # Find an initialize a record setting an error if it can't be found.
+        def find_or_initialize_with_error_by(attribute, value, error=:invalid) #:nodoc:
+          if value.present?
+            conditions = { attribute => value }
+            record = find(:first, :conditions => conditions)
+          end
+
+          unless record
+            record = new
+            if value.present?
+              record.send(:"#{attribute}=", value)
+            else
+              error = :blank
+            end
+            record.errors.add(attribute, error)
+          end
+
+          record
+        end
       end
     end
   end