Use https:// URLs when referring to python.org hosts.
diff --git a/Doc/library/datetime.rst b/Doc/library/datetime.rst
index db95269..15a4fe4 100644
--- a/Doc/library/datetime.rst
+++ b/Doc/library/datetime.rst
@@ -1563,7 +1563,7 @@
 
 .. seealso::
 
-   `pytz <http://pypi.python.org/pypi/pytz/>`_
+   `pytz <https://pypi.python.org/pypi/pytz/>`_
       The standard library has no :class:`tzinfo` instances, but
       there exists a third-party library which brings the *IANA timezone
       database* (also known as the Olson database) to Python: *pytz*.