diff --git a/Lib/ldap/schema/models.py b/Lib/ldap/schema/models.py
index 2e84f48..208fe40 100644
--- a/Lib/ldap/schema/models.py
+++ b/Lib/ldap/schema/models.py
@@ -8,17 +8,17 @@
 
 from ldap.schema.tokenizer import split_tokens,extract_tokens
 
-NOT_HUMAN_READABLE_LDAP_SYNTAXES = {
-  '1.3.6.1.4.1.1466.115.121.1.4':None,  # Audio
-  '1.3.6.1.4.1.1466.115.121.1.5':None,  # Binary
-  '1.3.6.1.4.1.1466.115.121.1.8':None,  # Certificate
-  '1.3.6.1.4.1.1466.115.121.1.9':None,  # Certificate List
-  '1.3.6.1.4.1.1466.115.121.1.10':None, # Certificate Pair
-  '1.3.6.1.4.1.1466.115.121.1.23':None, # G3 FAX
-  '1.3.6.1.4.1.1466.115.121.1.28':None, # JPEG
-  '1.3.6.1.4.1.1466.115.121.1.40':None, # Octet String
-  '1.3.6.1.4.1.1466.115.121.1.49':None, # Supported Algorithm
-}
+NOT_HUMAN_READABLE_LDAP_SYNTAXES = set([
+  '1.3.6.1.4.1.1466.115.121.1.4',  # Audio
+  '1.3.6.1.4.1.1466.115.121.1.5',  # Binary
+  '1.3.6.1.4.1.1466.115.121.1.8',  # Certificate
+  '1.3.6.1.4.1.1466.115.121.1.9',  # Certificate List
+  '1.3.6.1.4.1.1466.115.121.1.10', # Certificate Pair
+  '1.3.6.1.4.1.1466.115.121.1.23', # G3 FAX
+  '1.3.6.1.4.1.1466.115.121.1.28', # JPEG
+  '1.3.6.1.4.1.1466.115.121.1.40', # Octet String
+  '1.3.6.1.4.1.1466.115.121.1.49', # Supported Algorithm
+])
 
 
 class SchemaElement:
@@ -325,7 +325,7 @@ def _set_attrs(self,l,d):
     self.desc = d['DESC'][0]
     self.x_subst = d['X-SUBST'][0]
     self.not_human_readable = \
-      NOT_HUMAN_READABLE_LDAP_SYNTAXES.has_key(self.oid) or \
+      self.oid in NOT_HUMAN_READABLE_LDAP_SYNTAXES or \
       d['X-NOT-HUMAN-READABLE'][0]=='TRUE'
     self.x_binary_transfer_required = d['X-BINARY-TRANSFER-REQUIRED'][0]=='TRUE'
     return
@@ -615,7 +615,7 @@ def __str__(self):
     return '( %s )' % ''.join(result)
 
 
-class Entry(UserDict.UserDict):
+class Entry(UserDict.IterableUserDict):
   """
   Schema-aware implementation of an LDAP entry class.
 
@@ -653,7 +653,7 @@ def update(self,dict):
       self[key] = dict[key]
 
   def __contains__(self,key):
-    return self.has_key(key)
+    return key in self
 
   def __getitem__(self,nameoroid):
     return self.data[self._at2key(nameoroid)]
@@ -671,7 +671,7 @@ def __delitem__(self,nameoroid):
 
   def has_key(self,nameoroid):
     k = self._at2key(nameoroid)
-    return self.data.has_key(k)
+    return k in self.data
 
   def get(self,nameoroid,failobj):
     try:
diff --git a/Lib/ldap/schema/subentry.py b/Lib/ldap/schema/subentry.py
index b5e04c2..99a0dc4 100644
--- a/Lib/ldap/schema/subentry.py
+++ b/Lib/ldap/schema/subentry.py
@@ -298,7 +298,7 @@ def get_structural_oc(self,oc_list):
     while struct_oc_list:
       oid = struct_oc_list.pop()
       for child_oid in oc_tree[oid]:
-        if struct_ocs.has_key(self.getoid(ObjectClass,child_oid)):
+        if self.getoid(ObjectClass,child_oid) in struct_ocs:
           break
       else:
         result = oid
@@ -365,7 +365,7 @@ def attribute_types(
       object_class_oid = object_class_oids.pop(0)
       # Check whether the objectClass with this OID
       # has already been processed
-      if oid_cache.has_key(object_class_oid):
+      if object_class_oid in oid_cache:
         continue
       # Cache this OID as already being processed
       oid_cache[object_class_oid] = None
@@ -418,7 +418,7 @@ def attribute_types(
     # Remove all mandantory attribute types from
     # optional attribute type list
     for a in r_may.keys():
-      if r_must.has_key(a):
+      if a in r_must:
         del r_may[a]
 
     # Apply attr_type_filter to results