diff --git a/core/lib/Drupal/Core/Entity/EntityDefinitionUpdateManagerInterface.php b/core/lib/Drupal/Core/Entity/EntityDefinitionUpdateManagerInterface.php
index 55942c098991f72e56fac8589c5e3a556af837ad..0a6dc5d6b2141ddb0e25398d36b1b71248e8482a 100644
--- a/core/lib/Drupal/Core/Entity/EntityDefinitionUpdateManagerInterface.php
+++ b/core/lib/Drupal/Core/Entity/EntityDefinitionUpdateManagerInterface.php
@@ -107,8 +107,8 @@ public function getChangeList();
    * @param string $entity_type_id
    *   The entity type identifier.
    *
-   * @return \Drupal\Core\Entity\EntityTypeInterface
-   *   The entity type definition.
+   * @return \Drupal\Core\Entity\EntityTypeInterface|null
+   *   The entity type definition. Or NULL if not found.
    */
   public function getEntityType($entity_type_id);