diff --git a/src/FixerConfiguration/FixerOption.php b/src/FixerConfiguration/FixerOption.php
index 9fc1ec2af38..0f2bc291357 100644
--- a/src/FixerConfiguration/FixerOption.php
+++ b/src/FixerConfiguration/FixerOption.php
@@ -22,7 +22,10 @@ final class FixerOption implements FixerOptionInterface
 
     private bool $isRequired;
 
-    private mixed $default = null;
+    /**
+     * @var null|mixed
+     */
+    private $default = null;
 
     /**
      * @var null|list<string>
diff --git a/src/FixerConfiguration/FixerOptionBuilder.php b/src/FixerConfiguration/FixerOptionBuilder.php
index 8f8bb7405e8..e91c0b49ad4 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 $default = null;
 
     private bool $isRequired = true;
 
diff --git a/tests/Test/AbstractFixerWithAliasedOptionsTestCase.php b/tests/Test/AbstractFixerWithAliasedOptionsTestCase.php
index 99429c652a3..281f604686d 100644
--- a/tests/Test/AbstractFixerWithAliasedOptionsTestCase.php
+++ b/tests/Test/AbstractFixerWithAliasedOptionsTestCase.php
@@ -46,10 +46,6 @@ protected function doTest(string $expected, ?string $input = null, ?\SplFileInfo
         parent::doTest($expected, $input, $file);
 
         if (null !== $this->fixerWithAliasedConfig) {
-            if (!$this->fixerWithAliasedConfig instanceof AbstractFixer) {
-                throw new \LogicException();
-            }
-
             $fixer = $this->fixer;
             $fixerWithAliasedConfig = $this->fixerWithAliasedConfig;
 
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
     {