diff --git a/Models/Supplier.php b/Models/Supplier.php
index 9afe478..06cff70 100644
--- a/Models/Supplier.php
+++ b/Models/Supplier.php
@@ -243,11 +243,11 @@ class Supplier
     /**
      * Get created at date time
      *
-     * @return \DateTime
+     * @return \DateTimeImmutable
      *
      * @since 1.0.0
      */
-    public function getCreatedAt() : \DateTimeInterface
+    public function getCreatedAt() : \DateTimeImmutable
     {
         return $this->createdAt;
     }