diff --git a/Exception/FileNotFoundException.php b/Exception/FileNotFoundException.php
index 48b640809..06b732b16 100644
--- a/Exception/FileNotFoundException.php
+++ b/Exception/FileNotFoundException.php
@@ -19,7 +19,7 @@
  */
 class FileNotFoundException extends IOException
 {
-    public function __construct(string $message = null, int $code = 0, \Throwable $previous = null, string $path = null)
+    public function __construct(?string $message = null, int $code = 0, ?\Throwable $previous = null, ?string $path = null)
     {
         if (null === $message) {
             if (null === $path) {
diff --git a/Exception/IOException.php b/Exception/IOException.php
index fea26e4dd..44254a819 100644
--- a/Exception/IOException.php
+++ b/Exception/IOException.php
@@ -22,7 +22,7 @@ class IOException extends \RuntimeException implements IOExceptionInterface
 {
     private $path;
 
-    public function __construct(string $message, int $code = 0, \Throwable $previous = null, string $path = null)
+    public function __construct(string $message, int $code = 0, ?\Throwable $previous = null, ?string $path = null)
     {
         $this->path = $path;
 
diff --git a/Filesystem.php b/Filesystem.php
index 23192bc74..037629f18 100644
--- a/Filesystem.php
+++ b/Filesystem.php
@@ -132,7 +132,7 @@ public function exists($files)
      *
      * @throws IOException When touch fails
      */
-    public function touch($files, int $time = null, int $atime = null)
+    public function touch($files, ?int $time = null, ?int $atime = null)
     {
         foreach ($this->toIterable($files) as $file) {
             if (!($time ? self::box('touch', $file, $time, $atime) : self::box('touch', $file))) {
@@ -534,7 +534,7 @@ public function makePathRelative(string $endPath, string $startPath)
      *
      * @throws IOException When file type is unknown
      */
-    public function mirror(string $originDir, string $targetDir, \Traversable $iterator = null, array $options = [])
+    public function mirror(string $originDir, string $targetDir, ?\Traversable $iterator = null, array $options = [])
     {
         $targetDir = rtrim($targetDir, '/\\');
         $originDir = rtrim($originDir, '/\\');
diff --git a/Path.php b/Path.php
index 9aa37355a..858e1623e 100644
--- a/Path.php
+++ b/Path.php
@@ -257,7 +257,7 @@ public static function getRoot(string $path): string
      * @param string|null $extension if specified, only that extension is cut
      *                               off (may contain leading dot)
      */
-    public static function getFilenameWithoutExtension(string $path, string $extension = null): string
+    public static function getFilenameWithoutExtension(string $path, ?string $extension = null): string
     {
         if ('' === $path) {
             return '';