diff --git a/attributs.py b/attributs.py
index 7287045..e79cce1 100644
--- a/attributs.py
+++ b/attributs.py
@@ -486,8 +486,19 @@ class mail(Attr):
     #def parse_value(self, mail, ldif):
     # pass
 
+class cn(Attr):
+    singlevalue = True
+    optional = False
+
+class dn(Attr):
+    singlevalue = True
+    optional = False
+
 CRANS_ATTRIBUTES= {
     'objectClass' : objectClass,
+    'cn' : cn,
+    'dn' : dn,
+
     'aid': aid,
     'uid': uid,
     'nom' : nom,