diff --git a/.dir-locals.el b/.dir-locals.el
index 8b21d4e40..a2d1dc48d 100644
--- a/.dir-locals.el
+++ b/.dir-locals.el
@@ -1,6 +1,7 @@
 ((c++-mode . (
   (c-file-style . "k&r")
   (c-basic-offset . 4)
+  (c-block-comment-prefix . "  ")
   (indent-tabs-mode . nil)
   (tab-width . 4)
   (show-trailing-whitespace . t)