diff --git a/tests/Feature/GraphQL/Fieldtypes/DateFieldtypeTest.php b/tests/Feature/GraphQL/Fieldtypes/DateFieldtypeTest.php
index ee2edbc39e..776cfee9b2 100644
--- a/tests/Feature/GraphQL/Fieldtypes/DateFieldtypeTest.php
+++ b/tests/Feature/GraphQL/Fieldtypes/DateFieldtypeTest.php
@@ -17,7 +17,7 @@ public function setUp(): void
 
         Carbon::macro('getToStringFormat', function () {
             // Carbon 2.x
-            if (isset(static::$toStringFormat)) {
+            if (property_exists(static::this(), 'toStringFormat')) {
                 return static::$toStringFormat;
             }