diff --git a/lisp/org-agenda.el b/lisp/org-agenda.el
index af3a972d0..9fe39c5c3 100644
--- a/lisp/org-agenda.el
+++ b/lisp/org-agenda.el
@@ -7927,7 +7927,7 @@ tags in the FILTER if any of the tags in FILTER are grouptags."
 		     filter)))
       (dolist (x filter)
 	(push (org-agenda-filter-effort-form x) f))))
-    (cons 'and (nreverse f))))
+    (cons (if (eq type 'category) 'or 'and) (nreverse f))))
 
 (defun org-agenda-filter-make-matcher-tag-exp (tags op)
   "Return a form associated to tag-expression TAGS.