diff --git a/pep-0272.txt b/pep-0272.txt
index 25ae5101a..8c9d86310 100644
--- a/pep-0272.txt
+++ b/pep-0272.txt
@@ -79,7 +79,7 @@ Specification
     key_size
 
         An integer value; the size of the keys required by this
-        module.  If key_size is zero, then the algorithm accepts
+        module.  If key_size is None, then the algorithm accepts
         arbitrary-length keys.  You cannot pass a key of length 0
         (that is, the null string '') as such a variable-length key.