diff --git a/Models/QAAnswer.php b/Models/QAAnswer.php
index 86b1f42..16bb896 100755
--- a/Models/QAAnswer.php
+++ b/Models/QAAnswer.php
@@ -242,11 +242,11 @@ class QAAnswer implements \JsonSerializable
     /**
      * Get created at
      *
-     * @return \DateTime
+     * @return \DateTimeImmutable
      *
      * @since 1.0.0
      */
-    public function getCreatedAt() : \DateTimeInterface
+    public function getCreatedAt() : \DateTimeImmutable
     {
         return $this->createdAt;
     }
diff --git a/Models/QAQuestion.php b/Models/QAQuestion.php
index 231e6e7..ab204db 100755
--- a/Models/QAQuestion.php
+++ b/Models/QAQuestion.php
@@ -320,11 +320,11 @@ class QAQuestion implements \JsonSerializable
     /**
      * Get created at date time
      *
-     * @return \DateTime
+     * @return \DateTimeImmutable
      *
      * @since 1.0.0
      */
-    public function getCreatedAt() : \DateTimeInterface
+    public function getCreatedAt() : \DateTimeImmutable
     {
         return $this->createdAt;
     }