diff --git a/src/Models/Media.php b/src/Models/Media.php
index e04be32..3c00527 100644
--- a/src/Models/Media.php
+++ b/src/Models/Media.php
@@ -69,7 +69,7 @@ protected function fileName(): Attribute
         return Attribute::make(
             set: function ($value) {
                 $fileName = sha1($value.microtime());
-                $ext = pathinfo($value, PATHINFO_EXTENSION);
+                $ext = strtolower(pathinfo($value, PATHINFO_EXTENSION));
 
                 return "$fileName.$ext";
             },
diff --git a/tests/FileStorageTest.php b/tests/FileStorageTest.php
index 1b6ca7d..4558dc8 100644
--- a/tests/FileStorageTest.php
+++ b/tests/FileStorageTest.php
@@ -36,7 +36,7 @@ protected function setUp(): void
 
         $this->fileStorage = new FileStorage($config);
 
-        $path = __DIR__.'/TestSupport/assets/avatar.jpg';
+        $path = __DIR__.'/TestSupport/assets/avatar.JPG';
         $this->testFile = UploadedFile::fake()->create($path, file_get_contents($path));
 
         Queue::fake();
@@ -54,6 +54,7 @@ public function testCreateMedia(): void
 
         $this->assertNull($media->preview);
         $this->assertSame($media->type, TestDocumentType::AVATAR->value);
+        $this->assertSame('jpg', pathinfo($media->file_name, PATHINFO_EXTENSION));
 
         Queue::assertPushedWithChain(OptimizeImage::class, [
             GeneratePreview::class,
@@ -66,7 +67,7 @@ public function testUpdateMedia(): void
         $originalMedia = Media::factory()->create([
             'model_type' => 'App/Models/User',
             'model_id' => 1,
-            'file_name' => 'fake-file.jpg',
+            'file_name' => 'fake-file.JPG',
             'type' => TestDocumentType::AVATAR,
         ]);
 
diff --git a/tests/TestSupport/assets/avatar.jpg b/tests/TestSupport/assets/avatar.JPG
similarity index 100%
rename from tests/TestSupport/assets/avatar.jpg
rename to tests/TestSupport/assets/avatar.JPG