diff --git a/core/modules/system/lib/Drupal/system/Tests/Serialization/EntitySerializationTest.php b/core/modules/system/lib/Drupal/system/Tests/Serialization/EntitySerializationTest.php
index 89fa5ce..97c6f29 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Serialization/EntitySerializationTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Serialization/EntitySerializationTest.php
@@ -23,7 +23,7 @@ class EntitySerializationTest extends WebTestBase {
    *
    * @var array
    */
-  public static $modules = array('entity_test');
+  public static $modules = array('entity_test', 'serialization');
 
   /**
    * The test values.
diff --git a/core/modules/system/lib/Drupal/system/Tests/Serialization/SerializationTest.php b/core/modules/system/lib/Drupal/system/Tests/Serialization/SerializationTest.php
index 0a69208..425f0b0 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Serialization/SerializationTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Serialization/SerializationTest.php
@@ -17,12 +17,12 @@ class SerializationTest extends WebTestBase {
    *
    * @var array
    */
-  public static $modules = array('serialization_test');
+  public static $modules = array('serialization', 'serialization_test');
 
   /**
    * The serializer service to test.
    *
-   * @var Symfony\Component\Serializer\SerializerInterface
+   * @var \Symfony\Component\Serializer\SerializerInterface
    */
   protected $serializer;