diff --git a/Lib/email/Charset.py b/Lib/email/Charset.py
index 4a7ef695766..9a54dab9ef8 100644
--- a/Lib/email/Charset.py
+++ b/Lib/email/Charset.py
@@ -7,8 +7,10 @@
     def _is_unicode(x):
         return 1==0
 else:
+    # Use UnicodeType instead of built-in unicode for Py2.1 compatibility
+    from types import UnicodeType
     def _is_unicode(x):
-        return isinstance(x, unicode)
+        return isinstance(x, UnicodeType)
     
 from email.Encoders import encode_7or8bit
 import email.base64MIME