diff --git a/src/Plugin/Field/FieldFormatter/DateRangeTimezone.php b/src/Plugin/Field/FieldFormatter/DateRangeTimezone.php
index eb9bb31..4917ad5 100644
--- a/src/Plugin/Field/FieldFormatter/DateRangeTimezone.php
+++ b/src/Plugin/Field/FieldFormatter/DateRangeTimezone.php
@@ -93,8 +93,8 @@ class DateRangeTimezone extends FormatterBase implements ContainerFactoryPluginI
     foreach ($items as $delta => $item) {
       $build[$delta] = [
         '#theme' => 'datetime_range_timezone',
-        '#start_date' => $this->formatDate($item->start_date, $item->timezone),
-        '#end_date' => $this->formatDate($item->end_date, $item->timezone),
+        '#start_date' => $item->start_date ? $this->formatDate($item->start_date, $item->timezone) : '',
+        '#end_date' => $item->end_date ? $this->formatDate($item->end_date, $item->timezone) : '',
         '#separator' => $this->getSetting('separator'),
         '#timezone' => $this->getSetting('display_timezone') && $item->timezone ? system_time_zones()[$item->timezone] : NULL,
       ];