Issue #13883: PYTHONCASEOK also works with OS X.
diff --git a/Doc/using/cmdline.rst b/Doc/using/cmdline.rst
index d9cf954..8a02b76 100644
--- a/Doc/using/cmdline.rst
+++ b/Doc/using/cmdline.rst
@@ -450,7 +450,7 @@
 .. envvar:: PYTHONCASEOK
 
    If this is set, Python ignores case in :keyword:`import` statements.  This
-   only works on Windows.
+   only works on Windows and OS X.
 
 
 .. envvar:: PYTHONDONTWRITEBYTECODE