diff --git a/lc_ldap.py b/lc_ldap.py
index deed01f..1a2e1e6 100644
--- a/lc_ldap.py
+++ b/lc_ldap.py
@@ -531,24 +531,33 @@ class proprio(CransLdapObject):
     mfields = [ 'paiement', 'info', 'blacklist', 'controle']
     ofields = []
     xfields = []
-    _machines = None
+
+    def __init__(self, conn, dn, mode='ro', ldif = None):
+        super(proprio, self).__init__(conn, dn, mode, ldif)
+        self._machines = []
+
     def machines(self):
-        if self._machines == None:
+        if not self._machines:
             self._machines = self.conn.search_s('mid=*', dn = self.dn, scope = 1)
             for m in self._machines:
                 m._proprio = self
         return self._machines
 
 class machine(CransLdapObject):
-    _proprio = None
     ufields = ['mid', 'macAddress', 'host', 'midType']
     ofields = []
     mfields = ['info', 'blacklist', 'hostAlias', 'exempt',
                'portTCPout', 'portTCPin', 'portUDPout', 'portUDPin']
     xfields = ['ipHostNumber']
+
+    def __init__(self, conn, dn, mode='ro', ldif = None):
+        super(machine, self).__init__(conn, dn, mode, ldif)
+        self._proprio = None
+
     def proprio(self):
         parent_dn = self.dn.split(',', 1)[1]
-        self._proprio = new_cransldapobject(self.conn, parent_dn, self.mode)
+        if not self._proprio:
+            self._proprio = new_cransldapobject(self.conn, parent_dn, self.mode)
         return self._proprio