diff --git a/src/Exceptions/MediaUpload/ConfigurationException.php b/src/Exceptions/MediaUpload/ConfigurationException.php
index c67a5f7..aabc80f 100644
--- a/src/Exceptions/MediaUpload/ConfigurationException.php
+++ b/src/Exceptions/MediaUpload/ConfigurationException.php
@@ -33,7 +33,7 @@ public static function unrecognizedSource($source): self
         return new self("Could not recognize source, `{$source}` provided.");
     }
 
-    public static function invalidSource(string $message, \Throwable $original = null): self
+    public static function invalidSource(string $message, ?\Throwable $original= null): self
     {
         return new self("Invalid source provided. {$message}", 0, $original);
     }
diff --git a/src/Exceptions/MediaUpload/FileNotFoundException.php b/src/Exceptions/MediaUpload/FileNotFoundException.php
index 275e73e..4470a20 100644
--- a/src/Exceptions/MediaUpload/FileNotFoundException.php
+++ b/src/Exceptions/MediaUpload/FileNotFoundException.php
@@ -7,7 +7,7 @@
 
 class FileNotFoundException extends MediaUploadException
 {
-    public static function fileNotFound(string $path, \Throwable $original = null): self
+    public static function fileNotFound(string $path, ?\Throwable $original = null): self
     {
         return new self("File `{$path}` does not exist.", 0, $original);
     }
diff --git a/src/Helpers/File.php b/src/Helpers/File.php
index ede7dd4..ef55961 100644
--- a/src/Helpers/File.php
+++ b/src/Helpers/File.php
@@ -30,7 +30,7 @@ public static function cleanDirname(string $path): string
      * @param  string $path
      * @return string
      */
-    public static function sanitizePath(string $path, string $language = null): string
+    public static function sanitizePath(string $path, ?string $language = null): string
     {
         $language = $language ?: App::currentLocale();
         return trim(
@@ -48,7 +48,7 @@ public static function sanitizePath(string $path, string $language = null): stri
      * @param  string $file
      * @return string
      */
-    public static function sanitizeFileName(string $file, string $language = null): string
+    public static function sanitizeFileName(string $file, ?string $language = null): string
     {
         $language = $language ?: App::currentLocale();
         return trim(
diff --git a/src/Media.php b/src/Media.php
index 8a50f7e..c4c9987 100644
--- a/src/Media.php
+++ b/src/Media.php
@@ -47,7 +47,7 @@
  * @method static Builder forPathOnDisk(string $disk, string $path)
  * @method static Builder unordered()
  * @method static Builder whereIsOriginal()
- * @method static Builder whereIsVariant(string $variant_name = null)
+ * @method static Builder whereIsVariant(?string $variant_name = null)
  */
 class Media extends Model
 {
@@ -305,7 +305,7 @@ public function scopeWhereIsOriginal(Builder $q): void
         $q->whereNull('original_media_id');
     }
 
-    public function scopeWhereIsVariant(Builder $q, string $variant_name = null): void
+    public function scopeWhereIsVariant(Builder $q, ?string $variant_name = null): void
     {
         $q->whereNotNull('original_media_id');
         if ($variant_name) {
@@ -431,7 +431,7 @@ public function isOriginal(): bool
      * @param string|null $variantName if specified, will check if the model if a specific kind of variant
      * @return bool
      */
-    public function isVariant(string $variantName = null): bool
+    public function isVariant(?string $variantName = null): bool
     {
         return $this->original_media_id !== null
             && (!$variantName || $this->variant_name === $variantName);
@@ -482,7 +482,7 @@ public function makeVariantOf($media, string $variantName): self
      * @return void
      * @throws MediaMoveException
      */
-    public function move(string $destination, string $filename = null): void
+    public function move(string $destination, ?string $filename = null): void
     {
         $this->getMediaMover()->move($this, $destination, $filename);
     }
@@ -507,7 +507,7 @@ public function rename(string $filename): void
      * @return Media
      * @throws MediaMoveException
      */
-    public function copyTo(string $destination, string $filename = null): self
+    public function copyTo(string $destination, ?string $filename = null): self
     {
         return $this->getMediaMover()->copyTo($this, $destination, $filename);
     }
@@ -525,7 +525,7 @@ public function copyTo(string $destination, string $filename = null): self
     public function moveToDisk(
         string $disk,
         string $destination,
-        string $filename = null,
+        ?string $filename = null,
         array $options = []
     ): void {
         $this->getMediaMover()
@@ -547,7 +547,7 @@ public function moveToDisk(
     public function copyToDisk(
         string $disk,
         string $destination,
-        string $filename = null,
+        ?string $filename = null,
         array $options = []
     ): self {
         return $this->getMediaMover()
diff --git a/src/MediaMover.php b/src/MediaMover.php
index 544d112..6966b08 100644
--- a/src/MediaMover.php
+++ b/src/MediaMover.php
@@ -30,7 +30,7 @@ public function __construct(FilesystemManager $filesystem)
      * @return void
      * @throws MediaMoveException If attempting to change the file extension or a file with the same name already exists at the destination
      */
-    public function move(Media $media, string $directory, string $filename = null): void
+    public function move(Media $media, string $directory, ?string $filename = null): void
     {
         $storage = $this->filesystem->disk($media->disk);
 
@@ -65,7 +65,7 @@ public function moveToDisk(
         Media $media,
         string $disk,
         string $directory,
-        string $filename = null,
+        ?string $filename = null,
         array $options = []
     ): void {
         if ($media->disk === $disk) {
@@ -113,7 +113,7 @@ public function moveToDisk(
      * @return Media
      * @throws MediaMoveException If a file with the same name already exists at the destination or it fails to copy the file
      */
-    public function copyTo(Media $media, string $directory, string $filename = null): Media
+    public function copyTo(Media $media, string $directory, ?string $filename = null): Media
     {
         $storage = $this->filesystem->disk($media->disk);
 
@@ -160,7 +160,7 @@ public function copyToDisk(
         Media $media,
         string $disk,
         string $directory,
-        string $filename = null,
+        ?string $filename = null,
         array $options = []
     ): Media {
         if ($media->disk === $disk) {
diff --git a/src/MediaUploader.php b/src/MediaUploader.php
index d96b626..4902828 100644
--- a/src/MediaUploader.php
+++ b/src/MediaUploader.php
@@ -88,7 +88,7 @@ public function __construct(
         FileSystemManager $filesystem,
         SourceAdapterFactory $factory,
         ImageManipulator $imageManipulator,
-        array $config = null
+        ?array $config = null
     ) {
         $this->filesystem = $filesystem;
         $this->factory = $factory;
diff --git a/tests/Integration/UrlGenerators/LocalUrlGeneratorTest.php b/tests/Integration/UrlGenerators/LocalUrlGeneratorTest.php
index 83ff151..7d727d7 100644
--- a/tests/Integration/UrlGenerators/LocalUrlGeneratorTest.php
+++ b/tests/Integration/UrlGenerators/LocalUrlGeneratorTest.php
@@ -86,7 +86,7 @@ public function test_it_checks_public_visibility_mock_disk(): void
 
     protected function setupGenerator(
         $disk = 'uploads',
-        bool $public = null
+        ?bool $public = null
     ): LocalUrlGenerator {
         /** @var Media $media */
         $media = factory(Media::class)->make(