diff --git a/Doc/using/cmdline.rst b/Doc/using/cmdline.rst
index 851c2eb..c73f1e0 100644
--- a/Doc/using/cmdline.rst
+++ b/Doc/using/cmdline.rst
@@ -453,7 +453,8 @@
 .. envvar:: PYTHONDONTWRITEBYTECODE
 
    If this is set, Python won't try to write ``.pyc`` or ``.pyo`` files on the
-   import of source modules.
+   import of source modules.  This is equivalent to specifying the :option:`-B`
+   option.
 
 
 .. envvar:: PYTHONIOENCODING