diff --git a/Doc/library/getopt.rst b/Doc/library/getopt.rst
index a666d0a..2c0fad9 100644
--- a/Doc/library/getopt.rst
+++ b/Doc/library/getopt.rst
@@ -63,8 +63,8 @@
    non-option argument is encountered.
 
    If the first character of the option string is '+', or if the environment
-   variable POSIXLY_CORRECT is set, then option processing stops as soon as a
-   non-option argument is encountered.
+   variable :envvar:`POSIXLY_CORRECT` is set, then option processing stops as
+   soon as a non-option argument is encountered.
 
    .. versionadded:: 2.3