diff --git a/Modules/clinic/posixmodule.c.h b/Modules/clinic/posixmodule.c.h
index 1c3e9bc6d61376..da190b870771e0 100644
--- a/Modules/clinic/posixmodule.c.h
+++ b/Modules/clinic/posixmodule.c.h
@@ -1328,7 +1328,8 @@ PyDoc_STRVAR(os_mkdir__doc__,
 "dir_fd may not be implemented on your platform.\n"
 "  If it is unavailable, using it will raise a NotImplementedError.\n"
 "\n"
-"The mode argument is ignored on Windows.");
+"The mode argument is ignored on Windows. Where it is used, the current umask\n"
+"value is first masked out.");
 
 #define OS_MKDIR_METHODDEF    \
     {"mkdir", (PyCFunction)(void(*)(void))os_mkdir, METH_FASTCALL|METH_KEYWORDS, os_mkdir__doc__},
@@ -9291,4 +9292,4 @@ os_waitstatus_to_exitcode(PyObject *module, PyObject *const *args, Py_ssize_t na
 #ifndef OS_WAITSTATUS_TO_EXITCODE_METHODDEF
     #define OS_WAITSTATUS_TO_EXITCODE_METHODDEF
 #endif /* !defined(OS_WAITSTATUS_TO_EXITCODE_METHODDEF) */
-/*[clinic end generated code: output=ddc35c3177c3b3ed input=a9049054013a1b77]*/
+/*[clinic end generated code: output=f8cdbd04ea0e3502 input=a9049054013a1b77]*/
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index f602ae5c589267..f92e2ae6290ad2 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -4494,12 +4494,13 @@ If dir_fd is not None, it should be a file descriptor open to a directory,
 dir_fd may not be implemented on your platform.
   If it is unavailable, using it will raise a NotImplementedError.
 
-The mode argument is ignored on Windows.
+The mode argument is ignored on Windows. Where it is used, the current umask
+value is first masked out.
 [clinic start generated code]*/
 
 static PyObject *
 os_mkdir_impl(PyObject *module, path_t *path, int mode, int dir_fd)
-/*[clinic end generated code: output=a70446903abe821f input=e965f68377e9b1ce]*/
+/*[clinic end generated code: output=a70446903abe821f input=a61722e1576fab03]*/
 {
     int result;
 #ifdef HAVE_MKDIRAT