diff --git a/gnu/packages/aux-files/emacs/comp-integrity.el b/gnu/packages/aux-files/emacs/comp-integrity.el
index a53b9dcc5f..1aa82384e0 100644
--- a/gnu/packages/aux-files/emacs/comp-integrity.el
+++ b/gnu/packages/aux-files/emacs/comp-integrity.el
@@ -1,3 +1,4 @@
+;; -*- lexical-binding: t; -*-
 (require 'ert)
 
 (eval-when-compile
diff --git a/gnu/packages/emacs.scm b/gnu/packages/emacs.scm
index 54c6436c58..9ab204ffc2 100644
--- a/gnu/packages/emacs.scm
+++ b/gnu/packages/emacs.scm
@@ -386,6 +386,7 @@
                   (lambda ()
                     (display
                      (string-append
+                      ";; -*- lexical-binding: t; -*-\n"
                       "(setq find-function-C-source-directory \"" dest "\")\n\n"
                       "(provide 'guix-emacs-c-source)")))))))
           (add-after 'install 'install-site-start
@@ -412,6 +413,7 @@
                   (lambda ()
                     (display
                      (string-append
+                      ";; -*- lexical-binding: t; -*-\n"
                       "(when (require 'guix-emacs nil t)\n"
                       "  (guix-emacs-autoload-packages 'no-reload)\n"
                       "  (advice-add 'package-load-all-descriptors"