diff --git a/build-aux/update-subdirs b/build-aux/update-subdirs
index 96712f0b32e..c0ecb848105 100755
--- a/build-aux/update-subdirs
+++ b/build-aux/update-subdirs
@@ -41,7 +41,7 @@ if [ "x$subdirs" = x ]; then
   rm -f subdirs.el
 else
   rm -f subdirs.el~
-  echo ";; In load-path, after this directory should come
+  echo ";; In load-path, after this directory should come  -*- lexical-binding: t -*-
 ;; certain of its subdirectories.  Here we specify them.
 (normal-top-level-add-to-load-path '($subdirs))
 ;; Local" "Variables: