diff --git a/core/modules/serialization/tests/src/Unit/Normalizer/EntityReferenceFieldItemNormalizerTest.php b/core/modules/serialization/tests/src/Unit/Normalizer/EntityReferenceFieldItemNormalizerTest.php
index c0c2e9f..582a4d9 100644
--- a/core/modules/serialization/tests/src/Unit/Normalizer/EntityReferenceFieldItemNormalizerTest.php
+++ b/core/modules/serialization/tests/src/Unit/Normalizer/EntityReferenceFieldItemNormalizerTest.php
@@ -78,6 +78,9 @@ public function testNormalize() {
     $entity->url('canonical')
       ->willReturn($test_url)
       ->shouldBeCalled();
+    $entity->uuid()
+      ->willReturn('UUID')
+      ->shouldBeCalled();
 
     $entity_reference = $this->prophesize(TypedDataInterface::class);
     $entity_reference->getValue()
@@ -92,6 +95,7 @@ public function testNormalize() {
 
     $expected = [
       'target_id' => ['value' => 'test'],
+      'target_uuid' => 'UUID',
       'url' => $test_url,
     ];
     $this->assertSame($expected, $normalized);