diff --git a/lisp/org-agenda.el b/lisp/org-agenda.el
index a8fc36ffd..03a3a0027 100644
--- a/lisp/org-agenda.el
+++ b/lisp/org-agenda.el
@@ -7928,8 +7928,10 @@ These will be lower-case, for filtering."
 argument EXPAND can be used for the TYPE tag and will expand the
 tags in the FILTER if any of the tags in FILTER are grouptags."
   (let ((multi-pos-cats
-	 (string-match-p "\++"
-	  (mapconcat (lambda (cat) (substring cat 0 1)) filter "")))
+	 (and (eq type 'category)
+	      (string-match-p "\\+.*\\+"
+			      (mapconcat (lambda (cat) (substring cat 0 1))
+					 filter ""))))
 	f f1)
     (cond
      ;; Tag filter