diff --git a/app/Core/Controller.php b/app/Core/Controller.php
index 9a14ba7..6683b62 100644
--- a/app/Core/Controller.php
+++ b/app/Core/Controller.php
@@ -22,7 +22,7 @@ abstract class Controller
         $this->message = $message;
     }
 
-    public function retorno($mensagem, $status = null, $dados = null)
+    public function retorno(string $mensagem, $status = null, $dados = null)
     {
         //{ "status": "success", "message": "register created!", "data": [ "id": 20 ] }
         $data = [];