diff --git a/src/Image.php b/src/Image.php
index e39e877..cceaf45 100644
--- a/src/Image.php
+++ b/src/Image.php
@@ -19,7 +19,7 @@ class Image
     /**
      * @var int
      */
-    private $quality;
+    private int $quality;
 
     /**
      * @var bool