diff --git a/src/Article.php b/src/Article.php
index 0c162cc..b37eb35 100644
--- a/src/Article.php
+++ b/src/Article.php
@@ -27,7 +27,7 @@ class Article
         $this->preCalc = $preCalc;
     }
 
-    public function getPreCalc()
+    public function getPreCalc(): PreCalc
     {
         return $this->preCalc;
     }