diff --git a/Doc/c-api/init_config.rst b/Doc/c-api/init_config.rst
index c51b157bbb3..b7298ba825d 100644
--- a/Doc/c-api/init_config.rst
+++ b/Doc/c-api/init_config.rst
@@ -443,7 +443,7 @@ PyConfig
       by ``--with-platlibdir``, overrideable by the ``PYTHONPLATLIBDIR``
       environment variable.
 
-      .. versionadded:: 3.10
+      .. versionadded:: 3.9
 
    .. c:member:: int buffered_stdio
 
diff --git a/Doc/using/cmdline.rst b/Doc/using/cmdline.rst
index 3e0797279d6..f91ab020da5 100644
--- a/Doc/using/cmdline.rst
+++ b/Doc/using/cmdline.rst
@@ -543,7 +543,7 @@ conflict.
    If this is set to a non-empty string, it overrides the :data:`sys.platlibdir`
    value.
 
-   .. versionadded:: 3.10
+   .. versionadded:: 3.9
 
 
 .. envvar:: PYTHONSTARTUP