diff --git a/src/Api/Controller/UploadFaviconController.php b/src/Api/Controller/UploadFaviconController.php
index 7278f789c..4469d82f6 100644
--- a/src/Api/Controller/UploadFaviconController.php
+++ b/src/Api/Controller/UploadFaviconController.php
@@ -9,9 +9,13 @@
 
 namespace Flarum\Api\Controller;
 
+use Flarum\Foundation\ValidationException;
+use Flarum\Settings\SettingsRepositoryInterface;
+use Illuminate\Contracts\Filesystem\Factory;
 use Intervention\Image\Image;
 use Intervention\Image\ImageManager;
 use Psr\Http\Message\UploadedFileInterface;
+use Symfony\Contracts\Translation\TranslatorInterface;
 
 class UploadFaviconController extends UploadImageController
 {
@@ -19,6 +23,22 @@ class UploadFaviconController extends UploadImageController
 
     protected $filenamePrefix = 'favicon';
 
+    /**
+     * @var TranslatorInterface
+     */
+    protected $translator;
+
+    /**
+     * @param SettingsRepositoryInterface $settings
+     * @param Factory $filesystemFactory
+     */
+    public function __construct(SettingsRepositoryInterface $settings, Factory $filesystemFactory, TranslatorInterface $translator)
+    {
+        parent::__construct($settings, $filesystemFactory);
+
+        $this->translator = $translator;
+    }
+
     /**
      * {@inheritdoc}
      */
@@ -27,18 +47,24 @@ class UploadFaviconController extends UploadImageController
         $this->fileExtension = pathinfo($file->getClientFilename(), PATHINFO_EXTENSION);
 
         if ($this->fileExtension === 'ico') {
-            $encodedImage = $file->getStream();
-        } else {
-            $manager = new ImageManager();
-
-            $encodedImage = $manager->make($file->getStream())->resize(64, 64, function ($constraint) {
-                $constraint->aspectRatio();
-                $constraint->upsize();
-            })->encode('png');
-
-            $this->fileExtension = 'png';
+            // @todo remove in 2.0
+            throw new ValidationException([
+                'message' => strtr($this->translator->trans('validation.mimes'), [
+                    ':attribute' => 'favicon',
+                    ':values' => 'jpeg,png,gif,webp',
+                ])
+            ]);
         }
 
+        $manager = new ImageManager();
+
+        $encodedImage = $manager->make($file->getStream())->resize(64, 64, function ($constraint) {
+            $constraint->aspectRatio();
+            $constraint->upsize();
+        })->encode('png');
+
+        $this->fileExtension = 'png';
+
         return $encodedImage;
     }
 }