diff --git a/Models/Calendar.php b/Models/Calendar.php
index f4e7bfd..0837332 100755
--- a/Models/Calendar.php
+++ b/Models/Calendar.php
@@ -53,7 +53,7 @@ class Calendar
     /**
      * Created at.
      *
-     * @var \DateTime
+     * @var \DateTimeImmutable
      * @since 1.0.0
      */
     private \DateTimeImmutable $createdAt;
diff --git a/Models/Event.php b/Models/Event.php
index 8115971..85c1def 100755
--- a/Models/Event.php
+++ b/Models/Event.php
@@ -55,7 +55,7 @@ class Event
     /**
      * Created.
      *
-     * @var \DateTime
+     * @var \DateTimeImmutable
      * @since 1.0.0
      */
     private \DateTimeImmutable $createdAt;
diff --git a/Models/Schedule.php b/Models/Schedule.php
index fc76e79..184f2da 100755
--- a/Models/Schedule.php
+++ b/Models/Schedule.php
@@ -119,7 +119,7 @@ class Schedule
     /**
      * Created at.
      *
-     * @var \DateTime
+     * @var \DateTimeImmutable
      * @since 1.0.0
      */
     private \DateTimeImmutable $createdAt;