diff --git a/core/modules/serialization/src/Normalizer/EntityReferenceFieldItemNormalizer.php b/core/modules/serialization/src/Normalizer/EntityReferenceFieldItemNormalizer.php
index ad5afce..887288f 100644
--- a/core/modules/serialization/src/Normalizer/EntityReferenceFieldItemNormalizer.php
+++ b/core/modules/serialization/src/Normalizer/EntityReferenceFieldItemNormalizer.php
@@ -29,6 +29,7 @@ public function normalize($field_item, $format = NULL, array $context = []) {
 
     /** @var \Drupal\Core\Entity\EntityInterface $entity */
     if ($entity = $field_item->get('entity')->getValue()) {
+      $values['target_type'] = $entity->getEntityTypeId();
       // Add the target entity UUID to the normalized output values.
       $values['target_uuid'] = $entity->uuid();
 
diff --git a/core/modules/serialization/tests/src/Unit/Normalizer/EntityReferenceFieldItemNormalizerTest.php b/core/modules/serialization/tests/src/Unit/Normalizer/EntityReferenceFieldItemNormalizerTest.php
index 582a4d9..64e6035 100644
--- a/core/modules/serialization/tests/src/Unit/Normalizer/EntityReferenceFieldItemNormalizerTest.php
+++ b/core/modules/serialization/tests/src/Unit/Normalizer/EntityReferenceFieldItemNormalizerTest.php
@@ -81,6 +81,9 @@ public function testNormalize() {
     $entity->uuid()
       ->willReturn('UUID')
       ->shouldBeCalled();
+    $entity->getEntityTypeId()
+      ->willReturn('test_type')
+      ->shouldBeCalled();
 
     $entity_reference = $this->prophesize(TypedDataInterface::class);
     $entity_reference->getValue()
@@ -95,6 +98,7 @@ public function testNormalize() {
 
     $expected = [
       'target_id' => ['value' => 'test'],
+      'target_type' => 'test_type',
       'target_uuid' => 'UUID',
       'url' => $test_url,
     ];