diff --git fullcalendar.module fullcalendar.module
index 39f7622..43cf8ce 100644
--- fullcalendar.module
+++ fullcalendar.module
@@ -314,7 +314,7 @@
   }
   return array(
     'field' => $field_name,
-    'allDay' => date_field_all_day($field, $instance, $date1, $date2),
+    'allDay' => date_is_all_day(date_format($date1, DATE_FORMAT_DATETIME), date_format($date2, DATE_FORMAT_DATETIME)),
     'start' => $date1,
     'end' => $date2,
     'nid' => $entity->nid,