diff --git a/core/lib/Drupal/Core/Entity/ContentEntityBase.php b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
index 5f1ccdf..c9de1bf 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityBase.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
@@ -24,7 +24,7 @@
  * @todo: Once all entity types have been converted, merge improvements into the
  * Entity class and overhaul the EntityInterface.
  */
-class ContentEntityBase extends Entity {
+class ContentEntityBase extends Entity implements ContentEntityInterface {
 
   /**
    * Status code indentifying a removed translation.
diff --git a/core/modules/contact/lib/Drupal/contact/MessageInterface.php b/core/modules/contact/lib/Drupal/contact/MessageInterface.php
index bf797e4..f4efb1c 100644
--- a/core/modules/contact/lib/Drupal/contact/MessageInterface.php
+++ b/core/modules/contact/lib/Drupal/contact/MessageInterface.php
@@ -7,12 +7,12 @@
 
 namespace Drupal\contact;
 
-use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Entity\ContentEntityInterface;
 
 /**
  * Provides an interface defining a contant message entity
  */
-interface MessageInterface extends EntityInterface {
+interface MessageInterface extends ContentEntityInterface {
 
   /**
    * Returns the category this contact message belongs to.