diff --git a/inc/caldav-REPORT-calquery.php b/inc/caldav-REPORT-calquery.php
index 61d63c56..84b511a8 100644
--- a/inc/caldav-REPORT-calquery.php
+++ b/inc/caldav-REPORT-calquery.php
@@ -157,18 +157,18 @@ function SqlFilterFragment( $filter, $components, $property = null, $parameter =
 //          $params[':time_range_end'] = $finish;
 //        }
         if ( isset($start) && isset($finish) ) {
-          $sql .= ' AND (rrule IS NOT NULL OR (dtstart < :time_range_end AND (dtend > :time_range_start ';
+          $sql .= ' AND (rrule IS NOT NULL OR dtstart IS NULL OR (dtstart < :time_range_end AND (dtend > :time_range_start ';
           $sql .= ' OR (dtend IS NULL AND dtstart > :time_range_start)))) ';
           $params[':time_range_start'] = $start;
           $params[':time_range_end'] = $finish;
         }
         elseif ( isset($start) ) {
-          $sql .= ' AND (rrule IS NOT NULL OR (dtend > :time_range_start ';
+          $sql .= ' AND (rrule IS NOT NULL OR dtstart IS NULL OR (dtend > :time_range_start ';
           $sql .= ' OR (dtend IS NULL AND dtstart > :time_range_start))) ';
           $params[':time_range_start'] = $start;
         }
         elseif ( isset($finish) ) {
-          $sql .= ' AND (rrule IS NOT NULL OR dtstart < :time_range_end) ';
+          $sql .= ' AND (rrule IS NOT NULL OR dtstart IS NULL OR dtstart < :time_range_end) ';
           $params[':time_range_end'] = $finish;
         }
         $need_range_filter = array(new RepeatRuleDateTime($start),new RepeatRuleDateTime($finish));