diff --git a/Models/Promotion.php b/Models/Promotion.php
index ca0921c..dec0e56 100755
--- a/Models/Promotion.php
+++ b/Models/Promotion.php
@@ -478,11 +478,11 @@ class Promotion
     /**
      * Get created at
      *
-     * @return \DateTime
+     * @return \DateTimeImmutable
      *
      * @since 1.0.0
      */
-    public function getCreatedAt() : \DateTimeInterface
+    public function getCreatedAt() : \DateTimeImmutable
     {
         return $this->createdAt;
     }