diff --git a/share/man/man9/make_dev.9 b/share/man/man9/make_dev.9
index d846d57a1419..54b3ae1c9634 100644
--- a/share/man/man9/make_dev.9
+++ b/share/man/man9/make_dev.9
@@ -271,7 +271,9 @@ After
 .Fn destroy_dev
 is finished, and if the supplied
 .Fa cb
-is not NULL, the callback
+is not
+.Dv NULL ,
+the callback
 .Fa cb
 is called, with argument
 .Fa arg .