diff --git a/.dir-locals.el b/.dir-locals.el
new file mode 100644
index 000000000..614c284e9
--- /dev/null
+++ b/.dir-locals.el
@@ -0,0 +1,3 @@
+; https://www.gnu.org/software/emacs/manual/html_node/emacs/Directory-Variables.html#Directory-Variables
+((c++-mode . ((indent-tabs-mode . nil)
+              (c-basic-offset   . 4) )))