diff --git a/tests/Models/NullNavElementTest.php b/tests/Models/NullNavElementTest.php
index 08978f7..8fb07dc 100644
--- a/tests/Models/NullNavElementTest.php
+++ b/tests/Models/NullNavElementTest.php
@@ -47,6 +47,6 @@ final class NullNavElementTest extends \PHPUnit\Framework\TestCase
     public function testJsonSerialize() : void
     {
         $null = new NullNavElement(2);
-        self::assertEquals(['id' => 2], $null);
+        self::assertEquals(['id' => 2], $null->jsonSerialize());
     }
 }