diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index abf3e26..b28f28f 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -815,7 +815,7 @@
 
       from functools import partial
       with open('mydata.db', 'rb') as f:
-          for block in iter(partial(f.read, 64), ''):
+          for block in iter(partial(f.read, 64), b''):
               process_block(block)