diff --git a/src/CollectionExtension.php b/src/CollectionExtension.php
index 4585a8e..92e0807 100644
--- a/src/CollectionExtension.php
+++ b/src/CollectionExtension.php
@@ -19,6 +19,11 @@ class CollectionExtension
         return fn ($callback) => $this->registerCustomCallback('destroyed', $callback);
     }
 
+    public function convert()
+    {
+        return fn ($callback) => $this->registerCustomCallback('convert', $callback);
+    }
+
     public function after()
     {
         return fn ($callback) => $this->registerCustomCallback('after', $callback);
@@ -74,8 +79,10 @@ class CollectionExtension
             if (property_exists($this, 'customCallbacks')) {
                 return;
             }
+            $this->convertTo = null;
             $this->customCallbacks = collect([
                 'forceFileName' => fn ($model, $name) => $name,
+                'convert' => fn () => null,
                 'maxWidth' => fn ($size) => null,
                 'stored' => fn ($event) => true,
                 'after' => fn ($event) => true,
diff --git a/src/MediaController.php b/src/MediaController.php
index 7fc891b..761b97b 100644
--- a/src/MediaController.php
+++ b/src/MediaController.php
@@ -85,10 +85,13 @@ class MediaController
 
         $content = $isSingle ? [$request->input('payload')] : $request->input('payload');
 
-        $tempPaths = collect($content)->map(function ($c) use ($collection, $modelName) {
+        $tempPaths = collect($content)->map(function ($c) use ($collection) {
             $file = new MediaFile($c['name']);
 
             $tmpFile = $this->storeTemporaryFile($c['content'], $collection);
+            if ($collection->runCallback('convert') !== null) {
+                $file->setExtension($collection->runCallback('convert'));
+            }
             Storage::disk(config('media-library.temp_disk'))->move($tmpFile, 'media-library/' . $file->getFilename());
             return 'media-library/' . $file->getFilename();
         });
@@ -171,10 +174,16 @@ class MediaController
         $tmpFile = 'media-library/' . str()->uuid()->toString();
         Storage::disk(config('media-library.temp_disk'))->put($tmpFile, $binaryData);
 
+        $image = Image::load(Storage::disk(config('media-library.temp_disk'))->path($tmpFile));
         if (null !== $maxWidth && 'image/jpeg' === Storage::disk(config('media-library.temp_disk'))->mimeType($tmpFile)) {
-            Image::load(Storage::disk(config('media-library.temp_disk'))->path($tmpFile))->width($maxWidth)->save();
+            $image->width($maxWidth);
         }
 
+        if ($collection->runCallback('convert') !== null) {
+            $image->format($collection->runCallback('convert'));
+        }
+        $image->save();
+
         return $tmpFile;
     }
 
diff --git a/src/MediaFile.php b/src/MediaFile.php
index 784ff2a..6d04a14 100644
--- a/src/MediaFile.php
+++ b/src/MediaFile.php
@@ -25,6 +25,12 @@ class MediaFile
         $this->file = $newInstance->file;
     }
 
+    public function setExtension(string $extension): void
+    {
+        $newInstance = new self(($this->getPath() ? $this->getPath() . '/' : '') . $this->getBasename() . '.' . $extension);
+        $this->file = $newInstance->file;
+    }
+
     public function __call($method, $arguments)
     {
         return $this->file->{$method}(...$arguments);
diff --git a/tests/Feature/DeferredUploadTest.php b/tests/Feature/DeferredUploadTest.php
index 03948df..002d3a3 100644
--- a/tests/Feature/DeferredUploadTest.php
+++ b/tests/Feature/DeferredUploadTest.php
@@ -26,6 +26,28 @@ test('it uploads a deferred file to a collection', function () {
     Storage::disk('temp')->assertExists('media-library/beispiel.pdf');
 });
 
+test('it forces filename when uploading', function () {
+    $this->auth()->registerModel()->withoutExceptionHandling();
+
+    $this->postJson('/mediaupload', [
+        'parent' => ['model' => 'post', 'collection_name' => 'singleJpegFile', 'id' => null],
+        'payload' => ['content' => base64_encode($this->pngFile()->getContent()), 'name' => 'beispiel.png'],
+    ])
+        ->assertStatus(201)
+        ->assertExactJson([
+            'is_deferred' => true,
+            'original_url' => Storage::disk('temp')->url('media-library/beispiel.jpg'),
+            'name' => 'beispiel',
+            'collection_name' => 'singleJpegFile',
+            'size' => 366471,
+            'file_name' => 'beispiel.jpg',
+            'mime_type' => 'image/jpeg',
+            'icon' => url('storage/filetypes/imagejpeg.svg'),
+        ]);
+    Storage::disk('temp')->assertExists('media-library/beispiel.jpg');
+    Storage::disk('temp')->assertMissing('media-library/beispiel.png');
+});
+
 test('it stores a file to media library after deferred upload', function () {
     Carbon::setTestNow(Carbon::parse('2023-05-06 06:00:00'));
     $this->auth()->registerModel()->withoutExceptionHandling();
diff --git a/tests/TestCase.php b/tests/TestCase.php
index 7211518..bb1e66c 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -27,6 +27,11 @@ class TestCase extends BaseTestCase
         return $this->getFile('jpg.jpg', $filename ?: 'jpg.jpg');
     }
 
+    protected function pngFile(?string $filename = null): File
+    {
+        return $this->getFile('png.png', $filename ?: 'png.png');
+    }
+
     protected function getFile(string $location, string $as): File
     {
         $path = __DIR__ . '/stubs/' . $location;
diff --git a/tests/stubs/png.png b/tests/stubs/png.png
new file mode 100644
index 0000000..3ec45e5
Binary files /dev/null and b/tests/stubs/png.png differ
diff --git a/tests/workbench/app/Models/Post.php b/tests/workbench/app/Models/Post.php
index be93974..5764a48 100644
--- a/tests/workbench/app/Models/Post.php
+++ b/tests/workbench/app/Models/Post.php
@@ -23,6 +23,7 @@ class Post extends Model implements HasMedia
     public function registerMediaCollections(): void
     {
         $this->addMediaCollection('defaultSingleFile')->maxWidth(fn () => 250)->singleFile();
+        $this->addMediaCollection('singleJpegFile')->convert(fn () => 'jpg')->singleFile();
 
         $this->addMediaCollection('conversionsWithDefault')
             ->singleFile()