diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index 3b3c7dd..dec76d3 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -880,8 +880,8 @@
    to use the system default, which is usually line buffered for tty devices and
    fully buffered for other files.  If omitted, the system default is used. [#]_
 
-   Modes ``'r+'``, ``'w+'`` and ``'a+'`` open the file for updating (note that
-   ``'w+'`` truncates the file).  Append ``'b'`` to the mode to open the file in
+   Modes ``'r+'``, ``'w+'`` and ``'a+'`` open the file for updating (reading and writing);
+   note that ``'w+'`` truncates the file.  Append ``'b'`` to the mode to open the file in
    binary mode, on systems that differentiate between binary and text files; on
    systems that don't have this distinction, adding the ``'b'`` has no effect.