diff --git a/ldap/files/dynldap.py b/ldap/files/dynldap.py
index d02ea46..0fcd766 100644
--- a/ldap/files/dynldap.py
+++ b/ldap/files/dynldap.py
@@ -153,7 +153,7 @@ class  LdapEntry:
         if key[0] == '_':
             self.__dict__[key] = value
         elif value is None:
-            del(self.__dict__[key])
+            self._del(key)
         else:
             if not isinstance(value, ListType):
                 value = [ value ]