diff --git a/Doc/whatsnew/3.11.rst b/Doc/whatsnew/3.11.rst
index 1b736c71c24..8f0f6f83c01 100644
--- a/Doc/whatsnew/3.11.rst
+++ b/Doc/whatsnew/3.11.rst
@@ -276,6 +276,9 @@ Build Changes
 Deprecated
 ==========
 
+* The :mod:`lib2to3` package is now deprecated and may not be able to parse
+  Python 3.10 or newer. See the :pep:`617` (New PEG parser for CPython).
+  (Contributed by Victor Stinner in :issue:`40360`.)
 
 
 Removed
diff --git a/Lib/lib2to3/__init__.py b/Lib/lib2to3/__init__.py
index 4224dffef42..177405c8090 100644
--- a/Lib/lib2to3/__init__.py
+++ b/Lib/lib2to3/__init__.py
@@ -3,6 +3,6 @@
 
 warnings.warn(
     "lib2to3 package is deprecated and may not be able to parse Python 3.10+",
-    PendingDeprecationWarning,
+    DeprecationWarning,
     stacklevel=2,
 )
diff --git a/Lib/test/test_lib2to3.py b/Lib/test/test_lib2to3.py
index fd12a7e7acb..6ea8aa4a56e 100644
--- a/Lib/test/test_lib2to3.py
+++ b/Lib/test/test_lib2to3.py
@@ -2,7 +2,7 @@
 from test.support.import_helper import import_fresh_module
 from test.support.warnings_helper import check_warnings
 
-with check_warnings(("", PendingDeprecationWarning)):
+with check_warnings(("", DeprecationWarning)):
     load_tests = import_fresh_module('lib2to3.tests', fresh=['lib2to3']).load_tests
 
 if __name__ == '__main__':
diff --git a/Misc/NEWS.d/next/Library/2021-09-02-00-18-32.bpo-40360.9nmMtB.rst b/Misc/NEWS.d/next/Library/2021-09-02-00-18-32.bpo-40360.9nmMtB.rst
new file mode 100644
index 00000000000..4e9422dc06d
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-09-02-00-18-32.bpo-40360.9nmMtB.rst
@@ -0,0 +1,3 @@
+The :mod:`lib2to3` package is now deprecated and may not be able to parse
+Python 3.10 or newer. See the :pep:`617` (New PEG parser for CPython). Patch
+by Victor Stinner.