diff --git a/Lib/ldap/schema/subentry.py b/Lib/ldap/schema/subentry.py
index 2a42b4c..1c10d21 100644
--- a/Lib/ldap/schema/subentry.py
+++ b/Lib/ldap/schema/subentry.py
@@ -11,8 +11,7 @@
 SCHEMA_CLASS_MAPPING = ldap.cidict.cidict()
 SCHEMA_ATTR_MAPPING = {}
 
-for _name in dir():
-  o = eval(_name)
+for o in list(vars().values()):
   if hasattr(o,'schema_attribute'):
     SCHEMA_CLASS_MAPPING[o.schema_attribute] = o
     SCHEMA_ATTR_MAPPING[o] = o.schema_attribute