diff --git a/app/models/principal.rb b/app/models/principal.rb
index ff9b686..9ec0f6f 100644
--- a/app/models/principal.rb
+++ b/app/models/principal.rb
@@ -27,7 +27,7 @@ class Principal < ActiveRecord::Base
   
   named_scope :like, lambda {|q| 
     s = "%#{q.to_s.strip.downcase}%"
-    {:conditions => ["LOWER(login) LIKE ? OR LOWER(firstname) LIKE ? OR LOWER(lastname) LIKE ? OR LOWER(mail) LIKE ?", s, s, s, s],
+    {:conditions => ["LOWER(login) LIKE :s OR LOWER(firstname) LIKE :s OR LOWER(lastname) LIKE :s OR LOWER(mail) LIKE :s", {:s => s}],
      :order => 'type, login, lastname, firstname, mail'
     }
   }