diff --git a/index.md b/index.md
index 1f2479ce90d3595c95b43b3cfaea7f7e99715428..a1fc94235fa0b8042f85d972a9dd52dcf0576a83 100644
--- a/index.md
+++ b/index.md
@@ -135,12 +135,12 @@ class Article
         $this->content = $content;
     }
 
-    public function getId()
+    public function getId(): int
     {
         return $this->id;
     }
 
-    public function getContent()
+    public function getContent(): string
     {
         return $this->content;
     }