diff --git a/tests/ArrayBasedFormatterTestCases.php b/tests/ArrayBasedFormatterTestCases.php
index c413bcf..ee18373 100644
--- a/tests/ArrayBasedFormatterTestCases.php
+++ b/tests/ArrayBasedFormatterTestCases.php
@@ -469,7 +469,7 @@ public function nullable_value_objects_flattened_validate(mixed $serialized): vo
     {
         $toTest = $this->arrayify($serialized);
 
-        self::assertTrue(isset($toTest['order_id']));
+        self::assertArrayHasKey('order_id', $toTest);
         self::assertNull($toTest['order_id']);
     }