diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index bf97dfd1f2f6b9..4507fbc8164dc8 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -2160,9 +2160,12 @@ features:
    for possible values of *mode*.  As of Python 3.3, this is equivalent to
    ``os.chmod(path, mode, follow_symlinks=False)``.
 
+   ``lchmod()`` is not part of POSIX, but Unix implementations may have it if
+   changing the mode of symbolic links is supported.
+
    .. audit-event:: os.chmod path,mode,dir_fd os.lchmod
 
-   .. availability:: Unix.
+   .. availability:: Unix, not Linux, FreeBSD >= 1.3, NetBSD >= 1.3, not OpenBSD
 
    .. versionchanged:: 3.6
       Accepts a :term:`path-like object`.