diff --git a/app/models/auth_source.rb b/app/models/auth_source.rb
index 2f651ad..47c121a 100644
--- a/app/models/auth_source.rb
+++ b/app/models/auth_source.rb
@@ -20,7 +20,8 @@ class AuthSource < ActiveRecord::Base
   
   validates_presence_of :name
   validates_uniqueness_of :name
-  validates_length_of :name, :host, :account_password, :maximum => 60
+  validates_length_of :name, :host, :maximum => 60
+  validates_length_of :account_password, :maximum => 60, :allow_nil => true
   validates_length_of :account, :base_dn, :maximum => 255
   validates_length_of :attr_login, :attr_firstname, :attr_lastname, :attr_mail, :maximum => 30