core/modules/hal/hal.services.yml                           |  4 +++-
 core/modules/hal/src/Normalizer/TimestampItemNormalizer.php | 10 ++++------
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/core/modules/hal/hal.services.yml b/core/modules/hal/hal.services.yml
index 66cf5ba..b2c898f 100644
--- a/core/modules/hal/hal.services.yml
+++ b/core/modules/hal/hal.services.yml
@@ -19,7 +19,9 @@ services:
     arguments: ['@entity.manager', '@http_client', '@hal.link_manager', '@module_handler']
   serializer.normalizer.timestamp_item.hal:
    class: Drupal\hal\Normalizer\TimestampItemNormalizer
-   deprecated: The "%service_id% service is deprecated in 8.5.0, use the serializer.normalizer.timestamp service instead.
+   tags:
+     # Priority must be higher than serializer.normalizer.field_item.hal.
+     - { name: normalizer, priority: 20, bc: bc_timestamp_normalizer_unix, bc_config_name: 'serialization.settings' }
   serializer.normalizer.entity.hal:
     class: Drupal\hal\Normalizer\ContentEntityNormalizer
     arguments: ['@hal.link_manager', '@entity.manager', '@module_handler']
diff --git a/core/modules/hal/src/Normalizer/TimestampItemNormalizer.php b/core/modules/hal/src/Normalizer/TimestampItemNormalizer.php
index 78ec5a3..be1a765 100644
--- a/core/modules/hal/src/Normalizer/TimestampItemNormalizer.php
+++ b/core/modules/hal/src/Normalizer/TimestampItemNormalizer.php
@@ -4,17 +4,16 @@
 
 use Drupal\Core\Field\FieldItemInterface;
 use Drupal\Core\Field\Plugin\Field\FieldType\TimestampItem;
+use Drupal\Core\TypedData\Plugin\DataType\Timestamp;
 use Drupal\serialization\Normalizer\TimeStampItemNormalizerTrait;
 
 /**
  * Converts values for TimestampItem to and from common formats for hal.
  *
- * @deprecated in 8.5.0, use \Drupal\serialization\Normalizer\TimestampNormalizer instead.
+ * Overrides FieldItemNormalizer to use\Drupal\serialization\Normalizer\TimestampNormalizer
  */
 class TimestampItemNormalizer extends FieldItemNormalizer {
 
-  use TimeStampItemNormalizerTrait;
-
   /**
    * The interface or class that this Normalizer supports.
    *
@@ -25,9 +24,8 @@ class TimestampItemNormalizer extends FieldItemNormalizer {
   /**
    * {@inheritdoc}
    */
-  protected function normalizedFieldValues(FieldItemInterface $field_item, $format, array $context) {
-    $normalized = parent::normalizedFieldValues($field_item, $format, $context);
-    return $this->processNormalizedValues($normalized);
+  protected function constructValue($data, $context) {
+    return $this->serializer->denormalize($data, Timestamp::class, NULL, $context);
   }
 
 }