diff --git a/src/Plugin/Field/FieldWidget/SmartDateWidgetBase.php b/src/Plugin/Field/FieldWidget/SmartDateWidgetBase.php
index 7c0980a4bd577c9e15bf5d4d14e5ae02c392bcae..1df182236388337883a969d88efd5ab08664aafe 100644
--- a/src/Plugin/Field/FieldWidget/SmartDateWidgetBase.php
+++ b/src/Plugin/Field/FieldWidget/SmartDateWidgetBase.php
@@ -139,8 +139,8 @@ class SmartDateWidgetBase extends DateTimeWidgetBase {
       }
       $defaults = $this->fieldDefinition->getDefaultValueLiteral()[0];
       $timezone = $items[$delta]->timezone ?? date_default_timezone_get();
-      $values['start'] = !empty($items[$delta]->value) ? DrupalDateTime::createFromTimestamp($items[$delta]->value, $timezone) : '';
-      $values['end'] = !empty($items[$delta]->end_value) ? DrupalDateTime::createFromTimestamp($items[$delta]->end_value, $timezone) : '';
+      $values['start'] = !empty($items[$delta]->value) && is_numeric($items[$delta]->value) ? DrupalDateTime::createFromTimestamp($items[$delta]->value, $timezone) : '';
+      $values['end'] = !empty($items[$delta]->end_value) && is_numeric($items[$delta]->end_value) ? DrupalDateTime::createFromTimestamp($items[$delta]->end_value, $timezone) : '';
       $values['duration'] = $items[$delta]->duration ?? $defaults['default_duration'];
       $values['timezone'] = $items[$delta]->timezone ?? '';
     }