diff --git a/lisp/startup.el b/lisp/startup.el
index 444d156e601..87aa10d5c20 100644
--- a/lisp/startup.el
+++ b/lisp/startup.el
@@ -293,7 +293,7 @@ override them.  Users can prevent loading `default.el' with the `-q'
 option or by setting `inhibit-default-init' in their own init files,
 but inhibiting `site-start.el' requires `--no-site-file', which
 is less convenient."
-  :type 'string
+  :type '(choice (const :tag "none" nil) string)
   :group 'initialization)
 
 (defconst iso-8859-n-locale-regexp "8859[-_]?\\([1-49]\\)"