diff --git a/calendar/classes/local/api.php b/calendar/classes/local/api.php
index e59f34e95ec..a29a429b099 100644
--- a/calendar/classes/local/api.php
+++ b/calendar/classes/local/api.php
@@ -325,6 +325,12 @@ class api {
                 'core_calendar_event_timestart_updated',
                 [$legacyevent, $moduleinstance]
             );
+
+            // Rebuild the course cache to make sure the updated dates are reflected.
+            $courseid = $event->get_course()->get('id');
+            $cmid = $event->get_course_module()->get('id');
+            \course_modinfo::purge_course_module_cache($courseid, $cmid);
+            rebuild_course_cache($courseid, true, true);
         }
 
         return $mapper->from_legacy_event_to_event($legacyevent);