diff --git a/core/modules/serialization/tests/src/Unit/Normalizer/NullNormalizerTest.php b/core/modules/serialization/tests/src/Unit/Normalizer/NullNormalizerTest.php
index 5706db4..e79c07f 100644
--- a/core/modules/serialization/tests/src/Unit/Normalizer/NullNormalizerTest.php
+++ b/core/modules/serialization/tests/src/Unit/Normalizer/NullNormalizerTest.php
@@ -38,6 +38,7 @@ protected function setUp() {
   }
 
   /**
+   * @covers ::__construct
    * @covers ::supportsNormalization
    */
   public function testSupportsNormalization() {