diff --git a/gnu/services.scm b/gnu/services.scm
index 7e322c5..9397232 100644
--- a/gnu/services.scm
+++ b/gnu/services.scm
@@ -426,9 +426,13 @@ directory."
                 (extensions
                  (list
                   (service-extension activation-service-type
-                                     (lambda (files)
-                                       (let ((etc
-                                              (files->etc-directory files)))
+                                     (lambda (files+procs)
+                                       (let* ((proc (apply compose
+                                                           (filter procedure?
+                                                                   files+procs)))
+                                              (files (filter pair? files+procs))
+                                              (etc
+                                               (files->etc-directory (proc files))))
                                          #~(activate-etc #$etc))))
                   (service-extension system-service-type etc-entry)))
                 (compose concatenate)