diff --git a/tests/Models/NullNewsArticleTest.php b/tests/Models/NullNewsArticleTest.php
index c86e4d7..fcf1962 100755
--- a/tests/Models/NullNewsArticleTest.php
+++ b/tests/Models/NullNewsArticleTest.php
@@ -47,6 +47,6 @@ final class NullNewsArticleTest extends \PHPUnit\Framework\TestCase
     public function testJsonSerialize() : void
     {
         $null = new NullNewsArticle(2);
-        self::assertEquals(['id' => 2], $null);
+        self::assertEquals(['id' => 2], $null->jsonSerialize());
     }
 }
diff --git a/tests/Models/NullNewsSeenTest.php b/tests/Models/NullNewsSeenTest.php
index de589e7..8adc33c 100755
--- a/tests/Models/NullNewsSeenTest.php
+++ b/tests/Models/NullNewsSeenTest.php
@@ -47,6 +47,6 @@ final class NullNewsSeenTest extends \PHPUnit\Framework\TestCase
     public function testJsonSerialize() : void
     {
         $null = new NullNewsSeen(2);
-        self::assertEquals(['id' => 2], $null);
+        self::assertEquals(['id' => 2], $null->jsonSerialize());
     }
 }