diff --git a/Doc/library/urllib.request.rst b/Doc/library/urllib.request.rst
index 3908bd1b14b..055cc820d09 100644
--- a/Doc/library/urllib.request.rst
+++ b/Doc/library/urllib.request.rst
@@ -16,7 +16,7 @@ authentication, redirections, cookies and more.
 The :mod:`urllib.request` module defines the following functions:
 
 
-.. function:: urlopen(url, data=None[, timeout], *, cafile=None, capath=None, cadefault=True)
+.. function:: urlopen(url, data=None[, timeout], *, cafile=None, capath=None, cadefault=False)
 
    Open the URL *url*, which can be either a string or a
    :class:`Request` object.
diff --git a/Misc/NEWS b/Misc/NEWS
index 07a7eab04a6..44f5db1d2a4 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -296,6 +296,9 @@ Tests
 Documentation
 -------------
 
+- Issue #17977: The documentation for the cadefault argument's default value
+  in urllib.request.urlopen() is fixed to match the code.
+
 - Issue #15940: Specify effect of locale on time functions.
 
 - Issue #6696: add documentation for the Profile objects, and improve