diff --git a/Doc/library/http.cookies.rst b/Doc/library/http.cookies.rst
index 5c3fbc8..7c85d09 100644
--- a/Doc/library/http.cookies.rst
+++ b/Doc/library/http.cookies.rst
@@ -228,6 +228,12 @@
       return a Morsel object instead of a dict.
 
 
+.. method:: Morsel.setdefault(key, value=None)
+
+   Raise an error if key is not a valid :rfc:`2109` attribute, otherwise
+   behave the same as :meth:`dict.setdefault`.
+
+
 .. _cookie-example:
 
 Example
diff --git a/Doc/whatsnew/3.5.rst b/Doc/whatsnew/3.5.rst
index d795a11..d33dfe8 100644
--- a/Doc/whatsnew/3.5.rst
+++ b/Doc/whatsnew/3.5.rst
@@ -679,8 +679,8 @@
   consistent:  morsel comparison now takes the :attr:`~http.cookies.Morsel.key`
   and :attr:`~http.cookies.Morsel.value` into account,
   :meth:`~http.cookies.Morsel.copy` now results in a
-  :class:`~http.cookies.Morsel` instance rather than a *dict*, and
-  :meth:`~http.cookies.Morsel.update` will no raise an exception if any of the
+  :class:`~http.cookies.Morsel` instance rather than a :class:`dict`, and
+  :meth:`~http.cookies.Morsel.update` will now raise an exception if any of the
   keys in the update dictionary are invalid.  In addition, the undocumented
   *LegalChars* parameter of :func:`~http.cookies.Morsel.set` is deprecated and
   is now ignored.  (:issue:`2211`)