diff --git a/packages/Config/RectorConfig.php b/packages/Config/RectorConfig.php
index 1af9fe3c9e9..882c4fda243 100644
--- a/packages/Config/RectorConfig.php
+++ b/packages/Config/RectorConfig.php
@@ -125,7 +125,7 @@ public function ruleWithConfiguration(string $rectorClass, array $configuration)
         $services = $this->services();
 
         // decorate with value object inliner so Symfony understands, see https://getrector.org/blog/2020/09/07/how-to-inline-value-object-in-symfony-php-config
-        array_walk_recursive($configuration, static function (mixed &$value) {
+        array_walk_recursive($configuration, static function (&$value) {
             if (is_object($value)) {
                 $value = ValueObjectInliner::inline($value);
             }
diff --git a/packages/Parallel/Application/ParallelFileProcessor.php b/packages/Parallel/Application/ParallelFileProcessor.php
index 1ed27e3d1e7..6df87da67d3 100644
--- a/packages/Parallel/Application/ParallelFileProcessor.php
+++ b/packages/Parallel/Application/ParallelFileProcessor.php
@@ -197,7 +197,7 @@ function (array $json) use (
                 $handleErrorCallable,
 
                 // 3. callable on exit
-                function (mixed $exitCode, string $stdErr) use (&$systemErrors, $processIdentifier): void {
+                function ($exitCode, string $stdErr) use (&$systemErrors, $processIdentifier): void {
                     $this->processPool->tryQuitProcess($processIdentifier);
                     if ($exitCode === Command::SUCCESS) {
                         return;
diff --git a/rules/CodingStyle/ClassNameImport/ShortNameResolver.php b/rules/CodingStyle/ClassNameImport/ShortNameResolver.php
index 6247d4f99af..ee20c1e5dfd 100644
--- a/rules/CodingStyle/ClassNameImport/ShortNameResolver.php
+++ b/rules/CodingStyle/ClassNameImport/ShortNameResolver.php
@@ -171,7 +171,7 @@ private function resolveFromStmtsDocBlocks(array $stmts): array
             $phpDocNodeTraverser->traverseWithCallable(
                 $phpDocInfo->getPhpDocNode(),
                 '',
-                static function (mixed $node) use (&$shortNames) {
+                static function ($node) use (&$shortNames) {
                     if ($node instanceof PhpDocTagNode) {
                         $shortName = trim($node->name, '@');
                         if (StringUtils::isMatch($shortName, self::BIG_LETTER_START_REGEX)) {
diff --git a/rules/TypeDeclaration/TypeAnalyzer/GenericClassStringTypeNormalizer.php b/rules/TypeDeclaration/TypeAnalyzer/GenericClassStringTypeNormalizer.php
index f78093c7450..5b533d8681d 100644
--- a/rules/TypeDeclaration/TypeAnalyzer/GenericClassStringTypeNormalizer.php
+++ b/rules/TypeDeclaration/TypeAnalyzer/GenericClassStringTypeNormalizer.php
@@ -30,7 +30,7 @@ public function __construct(
 
     public function normalize(Type $type): ArrayType | UnionType | Type
     {
-        $type = TypeTraverser::map($type, function (Type $type, mixed $callback): Type {
+        $type = TypeTraverser::map($type, function (Type $type, $callback): Type {
             if (! $type instanceof ConstantStringType) {
                 return $callback($type);
             }
diff --git a/src/DependencyInjection/CompilerPass/RemoveSkippedRectorsCompilerPass.php b/src/DependencyInjection/CompilerPass/RemoveSkippedRectorsCompilerPass.php
index 936fbf32097..a8bb5ec47b0 100644
--- a/src/DependencyInjection/CompilerPass/RemoveSkippedRectorsCompilerPass.php
+++ b/src/DependencyInjection/CompilerPass/RemoveSkippedRectorsCompilerPass.php
@@ -39,7 +39,7 @@ private function resolveSkippedRectorClasses(ContainerBuilder $containerBuilder)
     {
         $skipParameters = (array) $containerBuilder->getParameter(Option::SKIP);
 
-        return array_filter($skipParameters, fn (mixed $element): bool => $this->isRectorClass($element));
+        return array_filter($skipParameters, fn ($element): bool => $this->isRectorClass($element));
     }
 
     private function isRectorClass(mixed $element): bool
diff --git a/src/DependencyInjection/Loader/Configurator/RectorServiceConfigurator.php b/src/DependencyInjection/Loader/Configurator/RectorServiceConfigurator.php
index ebf4da34e82..9665e501b50 100644
--- a/src/DependencyInjection/Loader/Configurator/RectorServiceConfigurator.php
+++ b/src/DependencyInjection/Loader/Configurator/RectorServiceConfigurator.php
@@ -24,7 +24,7 @@ public function configure(array $configuration): self
         $this->ensureClassIsConfigurable($this->id);
 
         // decorate with value object inliner so Symfony understands, see https://getrector.org/blog/2020/09/07/how-to-inline-value-object-in-symfony-php-config
-        array_walk_recursive($configuration, static function (mixed &$value) {
+        array_walk_recursive($configuration, static function (&$value) {
             if (is_object($value)) {
                 $value = ValueObjectInliner::inline($value);
             }