diff --git a/core/modules/serialization/serialization.install b/core/modules/serialization/serialization.install
index 84be1768bf..afc3311b4c 100644
--- a/core/modules/serialization/serialization.install
+++ b/core/modules/serialization/serialization.install
@@ -17,7 +17,7 @@ function serialization_requirements($phase) {
       'severity' => REQUIREMENT_INFO,
     ];
 
-      if (\Drupal::config('serialization.settings')->get('bc_primitives_as_strings')) {
+    if (\Drupal::config('serialization.settings')->get('bc_primitives_as_strings')) {
       $requirements['serialization_as_strings']['value'] = t('Enabled');
       $requirements['serialization_as_strings']['description'] = t('The Serialization API is configured to output only string values for REST and other applications (instead of integers or Booleans when appropriate). <a href="https://www.drupal.org/node/2837696">Disabling this backwards compatibility mode</a> is recommended unless your sites or applications require string output.');
     }
diff --git a/core/modules/serialization/src/Normalizer/NormalizerBase.php b/core/modules/serialization/src/Normalizer/NormalizerBase.php
index 5e829f65e7..9385b99122 100644
--- a/core/modules/serialization/src/Normalizer/NormalizerBase.php
+++ b/core/modules/serialization/src/Normalizer/NormalizerBase.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\serialization\Normalizer;
 
+use Drupal\Core\Cache\CacheableDependencyInterface;
 use Symfony\Component\Serializer\Normalizer\NormalizerInterface;
 use Symfony\Component\Serializer\Normalizer\SerializerAwareNormalizer;
 
@@ -81,4 +82,18 @@ protected function checkFormat($format = NULL) {
     return in_array($format, (array) $this->format, TRUE);
   }
 
+  /**
+   * Adds cacheability if applicable.
+   *
+   * @param array $context
+   *   Context options for the normalizer.
+   * @param $data
+   *   The data that might have cacheability information.
+   */
+  protected function addCacheableDependency(array $context, $data) {
+    if ($data instanceof CacheableDependencyInterface && isset($context['cacheability'])) {
+      $context['cacheability']->addCacheableDependency($data);
+    }
+  }
+
 }
diff --git a/core/modules/serialization/src/Normalizer/PrimitiveDataNormalizer.php b/core/modules/serialization/src/Normalizer/PrimitiveDataNormalizer.php
index 86d92531ed..cce108cacf 100644
--- a/core/modules/serialization/src/Normalizer/PrimitiveDataNormalizer.php
+++ b/core/modules/serialization/src/Normalizer/PrimitiveDataNormalizer.php
@@ -2,7 +2,6 @@
 
 namespace Drupal\serialization\Normalizer;
 
-use Drupal\Core\Cache\CacheableDependencyInterface;
 use Drupal\Core\TypedData\PrimitiveInterface;
 
 /**
@@ -27,16 +26,7 @@ public function normalize($object, $format = NULL, array $context = []) {
     // getCastedValue would return NULL, but as typed data is not aware of real
     // optional values on the primitive level, we implement our own optional
     // value normalization here.
-    $value = $object->getValue();
-    if ($value === NULL) {
-      return NULL;
-    }
-    else {
-      if ($value instanceof CacheableDependencyInterface && isset($context['cacheability'])) {
-        $context['cacheability']->addCacheableDependency($value);
-      }
-      return $object->getCastedValue();
-    }
+    return $object->getValue() === NULL ? NULL : $object->getCastedValue();
   }
 
 }
diff --git a/core/modules/serialization/src/Normalizer/TypedDataNormalizer.php b/core/modules/serialization/src/Normalizer/TypedDataNormalizer.php
index 9603147780..958b987dc7 100644
--- a/core/modules/serialization/src/Normalizer/TypedDataNormalizer.php
+++ b/core/modules/serialization/src/Normalizer/TypedDataNormalizer.php
@@ -2,8 +2,6 @@
 
 namespace Drupal\serialization\Normalizer;
 
-use Drupal\Core\Cache\CacheableDependencyInterface;
-
 /**
  * Converts typed data objects to arrays.
  */
@@ -20,19 +18,8 @@ class TypedDataNormalizer extends NormalizerBase {
    * {@inheritdoc}
    */
   public function normalize($object, $format = NULL, array $context = []) {
-    $value = $object->getValue();
-    if ($value === NULL) {
-      return NULL;
-    }
-    else {
-      if ($value instanceof CacheableDependencyInterface && isset($context['cacheability'])) {
-        $context['cacheability']->addCacheableDependency($value);
-        return (string) $value;
-      }
-
-    }
-    return $value;
-
+    $this->addCacheableDependency($context, $object);
+    return $object->getValue();
   }
 
 }
diff --git a/core/modules/system/tests/modules/entity_test/src/TypedData/ComputedString.php b/core/modules/system/tests/modules/entity_test/src/TypedData/ComputedString.php
index 579e0a47fa..1767102d7a 100644
--- a/core/modules/system/tests/modules/entity_test/src/TypedData/ComputedString.php
+++ b/core/modules/system/tests/modules/entity_test/src/TypedData/ComputedString.php
@@ -2,36 +2,23 @@
 
 namespace Drupal\entity_test\TypedData;
 
+use Drupal\Core\Cache\Cache;
 use Drupal\Core\Cache\CacheableDependencyInterface;
-use Drupal\Core\Cache\RefinableCacheableDependencyTrait;
 use Drupal\Core\TypedData\TypedData;
 
-use Drupal\Core\Render\BubbleableMetadata;
-
 /**
  * A computed property for test strings.
  */
 class ComputedString extends TypedData implements CacheableDependencyInterface {
 
-  use RefinableCacheableDependencyTrait;
-
-  /**
-   * @var string
-   */
-  protected $computedValue;
-
   /**
    * {@inheritdoc}
    */
   public function getValue() {
     /** @var \Drupal\Core\Field\FieldItemInterface $item */
     $item = $this->getParent();
-    $this->cacheContexts = ['request_format'];
-    $this->cacheTags = ['you_are_it', 'no_tag_backs'];
-
-    $this->computedValue = "Computed! " . $item->get('value')->getString();
 
-    return $this;
+    return 'Computed! ' . $item->get('value')->getString();
   }
 
   /**
@@ -44,7 +31,21 @@ public function getCastedValue() {
   /**
    * {@inheritdoc}
    */
-  function __toString() {
-    return $this->computedValue;
+  public function getCacheTags() {
+    return ['you_are_it', 'no_tag_backs'];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheContexts() {
+    return ['request_format'];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheMaxAge() {
+    return Cache::PERMANENT;
   }
 }