diff --git a/Doc/library/http.cookies.rst b/Doc/library/http.cookies.rst
index c2bb80d5d19..56c52f8a8b2 100644
--- a/Doc/library/http.cookies.rst
+++ b/Doc/library/http.cookies.rst
@@ -141,7 +141,7 @@ Morsel Objects
    in HTTP requests, and is not accessible through JavaScript. This is intended
    to mitigate some forms of cross-site scripting.
 
-   The keys are case-insensitive.
+   The keys are case-insensitive and their default value is ``''``.
 
    .. versionchanged:: 3.5
       :meth:`~Morsel.__eq__` now takes :attr:`~Morsel.key` and :attr:`~Morsel.value`