diff --git a/src/FixerConfiguration/FixerOptionBuilder.php b/src/FixerConfiguration/FixerOptionBuilder.php
index 8f8bb7405e8..73bb98ecd6c 100644
--- a/src/FixerConfiguration/FixerOptionBuilder.php
+++ b/src/FixerConfiguration/FixerOptionBuilder.php
@@ -23,7 +23,7 @@ final class FixerOptionBuilder
     /**
      * @var null|mixed
      */
-    private mixed $default = null;
+    private ?mixed $default = null;
 
     private bool $isRequired = true;
 
diff --git a/tests/UtilsTest.php b/tests/UtilsTest.php
index beaf06dd3de..36d010b1dfd 100644
--- a/tests/UtilsTest.php
+++ b/tests/UtilsTest.php
@@ -34,7 +34,7 @@ final class UtilsTest extends TestCase
     /**
      * @var null|false|string
      */
-    private null|bool|string $originalValueOfFutureMode;
+    private $originalValueOfFutureMode;
 
     protected function setUp(): void
     {