PYTHONFSENCODING is not available on Windows or Mac OS X
diff --git a/Doc/using/cmdline.rst b/Doc/using/cmdline.rst
index 45c1040..28df51d 100644
--- a/Doc/using/cmdline.rst
+++ b/Doc/using/cmdline.rst
@@ -447,6 +447,10 @@
If this is set before running the interpreter, it overrides the encoding used
for the filesystem encoding (see :func:`sys.getfilesystemencoding`).
+ This variable is not available (ignored) on Windows and Mac OS X: the
+ filesystem encoding is pinned to ``'mbcs'`` on Windows and ``'utf-8'`` on
+ Mac OS X.
+
.. versionadded:: 3.2
diff --git a/Doc/whatsnew/3.2.rst b/Doc/whatsnew/3.2.rst
index 2ec93d2..bf65545 100644
--- a/Doc/whatsnew/3.2.rst
+++ b/Doc/whatsnew/3.2.rst
@@ -242,7 +242,9 @@
The filesystem encoding can be specified by setting the
:envvar:`PYTHONFSENCODING` environment variable before running the interpreter.
-The value should be a string in the form ``<encoding>``, e.g. ``utf-8``.
+The value is an encoding name, e.g. ``iso-8859-1``. This variable is not
+available (ignored) on Windows and Mac OS X: the filesystem encoding is pinned
+to ``'mbcs'`` on Windows and ``'utf-8'`` on Mac OS X.
The :mod:`os` module has two new functions: :func:`os.fsencode` and
:func:`os.fsdecode`.