diff --git a/app/models/principal.rb b/app/models/principal.rb
index 9ec0f6ff8..37d2a545d 100644
--- a/app/models/principal.rb
+++ b/app/models/principal.rb
@@ -33,6 +33,11 @@ class Principal < ActiveRecord::Base
   }
   
   def <=>(principal)
-    self.to_s.downcase <=> principal.to_s.downcase
+    if self.class.name == principal.class.name
+      self.to_s.downcase <=> principal.to_s.downcase
+    else
+      # groups after users
+      principal.class.name <=> self.class.name
+    end
   end
 end
diff --git a/app/models/user.rb b/app/models/user.rb
index e9c58bcc5..4cfa2b47b 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -214,11 +214,6 @@ class User < Principal
   def self.find_by_mail(mail)
     find(:first, :conditions => ["LOWER(mail) = ?", mail.to_s.downcase])
   end
-
-  # Sort users by their display names
-  def <=>(user)
-    self.to_s.downcase <=> user.to_s.downcase
-  end
   
   def to_s
     name