diff --git a/Models/Item.php b/Models/Item.php
index 7946987..db13715 100644
--- a/Models/Item.php
+++ b/Models/Item.php
@@ -69,7 +69,7 @@ class Item
      */
     public function __construct()
     {
-        $this->createdAt = new \DateTime('now');
+        $this->createdAt = new \DateTimeImmutable('now');
     }
 
     /**
@@ -91,7 +91,7 @@ class Item
      *
      * @since 1.0.0
      */
-    public function getCreatedAt() : \DateTime
+    public function getCreatedAt() : \DateTimeInterface
     {
         return $this->createdAt;
     }