diff --git a/sites/all/modules/date/date/date.theme b/sites/all/modules/date/date/date.theme
index 585a9b3..c8cabc8 100644
--- a/sites/all/modules/date/date/date.theme
+++ b/sites/all/modules/date/date/date.theme
@@ -258,7 +258,7 @@ function theme_date_all_day($field, $which, $date1, $date2, $format, $node, $vie
     return date_format_date($$which, 'custom', $format);
   }
   
-  if ($all_day == date_field_all_day($field, $date1, $date2)) {
+  if ($all_day = date_field_all_day($field, $date1, $date2)) {
     $format = date_limit_format($format, array('year', 'month', 'day'));
     return trim(date_format_date($$which, 'custom', $format) .' '. theme('date_all_day_label'));
   }