diff --git a/test/lisp/calendar/icalendar-tests.el b/test/lisp/calendar/icalendar-tests.el
index 27076f5ce1f..9071607005d 100644
--- a/test/lisp/calendar/icalendar-tests.el
+++ b/test/lisp/calendar/icalendar-tests.el
@@ -999,6 +999,9 @@ END:VALARM
 
 (ert-deftest icalendar-export-bug-56241-dotted-pair ()
   "See https://debbugs.gnu.org/cgi/bugreport.cgi?bug=56241#5"
+  ;; This test started failing early July 2023 without any apparent change
+  ;; to the underlying code, so is probably sensitive to the current date.
+  :tags '(:unstable)
   (let ((icalendar-export-sexp-enumeration-days 366))
     (mapc (lambda (diary-string)
             (should (string= "" (icalendar-tests--get-error-string-for-export