diff --git a/Lib/ldap/cidict.py b/Lib/ldap/cidict.py
index 68ac6f9..a9e6dee 100644
--- a/Lib/ldap/cidict.py
+++ b/Lib/ldap/cidict.py
@@ -6,10 +6,10 @@
 See https://www.python-ldap.org/ for details.
 """
 
-__version__ = """$Revision: 1.16 $"""
+__version__ = """$Revision: 1.17 $"""
 
 from UserDict import IterableUserDict
-from string import lower
+
 
 class cidict(IterableUserDict):
   """
@@ -22,15 +22,15 @@ def __init__(self,default=None):
     self.update(default or {})
 
   def __getitem__(self,key):
-    return self.data[lower(key)]
+    return self.data[key.lower()]
 
   def __setitem__(self,key,value):
-    lower_key = lower(key)
+    lower_key = key.lower()
     self._keys[lower_key] = key
     self.data[lower_key] = value
 
   def __delitem__(self,key):
-    lower_key = lower(key)
+    lower_key = key.lower()
     del self._keys[lower_key]
     del self.data[lower_key]
 
@@ -39,10 +39,10 @@ def update(self,dict):
       self[key] = dict[key]
 
   def has_key(self,key):
-    return IterableUserDict.has_key(self,lower(key))
+    return key in self
 
   def __contains__(self,key):
-    return self.has_key(key)
+    return IterableUserDict.__contains__(self, key.lower())
 
   def get(self,key,failobj=None):
     try:
diff --git a/Tests/t_cidict.py b/Tests/t_cidict.py
index ac56fd3..c8812f2 100644
--- a/Tests/t_cidict.py
+++ b/Tests/t_cidict.py
@@ -41,6 +41,7 @@ def test_cidict(self):
         del cix["abcdEF"]
         self.assertEqual("abcdef" in cix, False)
         self.assertEqual("AbCDef" in cix._keys, False)
+        self.assertEqual(cix.has_key("abcdef"), False)
 
 
 if __name__ == '__main__':