(gnus-permanently-visible-groups): Fix custom type.

diff --git a/lisp/gnus/gnus-group.el b/lisp/gnus/gnus-group.el
index 4eea2c01923143eb75332ac5b9885d603ecd3ff8..c881f5976d94871581543811b82ff71f409a979d 100644 (file)
--- a/lisp/gnus/gnus-group.el
+++ b/lisp/gnus/gnus-group.el
@@ -91,7 +91,7 @@ unread articles in the groups.
 
 If nil, no groups are permanently visible."
   :group 'gnus-group-listing
-  :type 'regexp)
+  :type '(choice regexp (const nil)))
 
 (defcustom gnus-list-groups-with-ticked-articles t
   "*If non-nil, list groups that have only ticked articles.