diff --git a/lisp/org-agenda.el b/lisp/org-agenda.el
index 2d1bafef7..d7e584155 100644
--- a/lisp/org-agenda.el
+++ b/lisp/org-agenda.el
@@ -7030,7 +7030,7 @@ their type."
 			       (org-cmp-ts a b "deadline")))
 	 (deadline-down   (if deadline-up (- deadline-up) nil))
 	 (tsia-up         (and (org-em 'tsia-up 'tsia-down ss)
-			       (org-cmp-ts a b "iatimestamp_ia")))
+			       (org-cmp-ts a b "timestamp_ia")))
 	 (tsia-down       (if tsia-up (- tsia-up) nil))
 	 (ts-up           (and (org-em 'ts-up 'ts-down ss)
 			       (org-cmp-ts a b "timestamp")))