diff --git a/core/lib/Drupal/Core/Entity/Element/EntityAutocomplete.php b/core/lib/Drupal/Core/Entity/Element/EntityAutocomplete.php
index b1bab9a..0e17c25 100644
--- a/core/lib/Drupal/Core/Entity/Element/EntityAutocomplete.php
+++ b/core/lib/Drupal/Core/Entity/Element/EntityAutocomplete.php
@@ -65,7 +65,7 @@ public static function valueCallback(&$element, $input, FormStateInterface $form
         $element['#default_value'] = array($element['#default_value']);
       }
 
-      if (!(reset($element['#default_value']) instanceof EntityInterface)) {
+      if ($element['#default_value'] && !(reset($element['#default_value']) instanceof EntityInterface)) {
         throw new \InvalidArgumentException('The #default_value property has to be an entity object or an array of entity objects.');
       }