diff -r 3a6b1186745f Doc/library/datetime.rst
--- a/Doc/library/datetime.rst	Fri Jan 01 23:27:38 2016 -0800
+++ b/Doc/library/datetime.rst	Sat Jan 02 17:39:14 2016 +0100
@@ -1950,7 +1950,8 @@
 
 (2)
    The :meth:`strptime` method can parse years in the full [1, 9999] range, but
-   years < 1000 must be zero-filled to 4-digit width.
+   years < 1000 must be zero-filled to 4-digit. Because the ``%Y`` directive
+   is inconsistent across different platforms, ``%4Y`` directive should be preferred.
 
    .. versionchanged:: 3.2
       In previous versions, :meth:`strftime` method was restricted to