diff --git a/core/modules/entity_reference/lib/Drupal/entity_reference/ConfigurableEntityReferenceItem.php b/core/modules/entity_reference/lib/Drupal/entity_reference/ConfigurableEntityReferenceItem.php
index c140904..c350955 100644
--- a/core/modules/entity_reference/lib/Drupal/entity_reference/ConfigurableEntityReferenceItem.php
+++ b/core/modules/entity_reference/lib/Drupal/entity_reference/ConfigurableEntityReferenceItem.php
@@ -12,6 +12,7 @@
 use Drupal\Core\Field\FieldDefinitionInterface;
 use Drupal\Core\Field\Plugin\Field\FieldType\EntityReferenceItem;
 use Drupal\Core\Session\AccountInterface;
+use Drupal\Core\TypedData\AllowedValuesInterface;
 use Drupal\Core\TypedData\DataDefinition;
 use Drupal\Core\Validation\Plugin\Validation\Constraint\AllowedValuesConstraint;
 
@@ -26,7 +27,7 @@
  *
  * @see entity_reference_field_info_alter().
  */
-class ConfigurableEntityReferenceItem extends EntityReferenceItem implements ConfigFieldItemInterface {
+class ConfigurableEntityReferenceItem extends EntityReferenceItem implements ConfigFieldItemInterface, AllowedValuesInterface {
 
   /**
    * {@inheritdoc}