diff --git a/objets.py b/objets.py
index 0a4dfd8..a5bdf5e 100644
--- a/objets.py
+++ b/objets.py
@@ -128,6 +128,7 @@ class CransLdapObject(object):
 
         self._modifs = {} # C'est là qu'on met les modifications
         self.dn = dn
+        self.parent_dn = dn.split(',', 1)[1] if ',' in dn else ''
 
         orig = {}
         if uldif:
@@ -805,9 +806,8 @@ class machine(CransLdapObject):
 
     def proprio(self, mode=None):
         u"""Renvoie le propriétaire de la machine"""
-        parent_dn = self.dn.split(',', 1)[1]
         if not self._proprio:
-            self._proprio = new_cransldapobject(self.conn, parent_dn, self.mode if mode is None else mode)
+            self._proprio = new_cransldapobject(self.conn, self.parent_dn, self.mode if mode is None else mode)
         return self._proprio
 
     def certificats(self):
@@ -1178,9 +1178,8 @@ class facture(CransLdapObject):
 
     def proprio(self):
         u"""Renvoie le propriétaire de la facture"""
-        parent_dn = self.dn.split(',', 1)[1]
         if not self._proprio:
-            self._proprio = new_cransldapobject(self.conn, parent_dn, self.mode)
+            self._proprio = new_cransldapobject(self.conn, self.parent_dn, self.mode)
         return self._proprio
 
 @crans_object
@@ -1254,9 +1253,8 @@ class baseCert(CransLdapObject):
 
     def machine(self):
         u"""Renvoie la machine du certificat"""
-        parent_dn = self.dn.split(',', 1)[1]
         if not self._machine:
-            self._machine = new_cransldapobject(self.conn, parent_dn, self.mode)
+            self._machine = new_cransldapobject(self.conn, self.parent_dn, self.mode)
         return self._machine