diff --git a/lib/private/Comments/Comment.php b/lib/private/Comments/Comment.php
index 0128dc8defd..c481e36f95b 100644
--- a/lib/private/Comments/Comment.php
+++ b/lib/private/Comments/Comment.php
@@ -351,13 +351,9 @@ class Comment implements IComment {
 	}
 
 	/**
-	 * sets the date of the most recent child
-	 *
-	 * @param \DateTime $dateTime
-	 * @return IComment
-	 * @since 9.0.0
+	 * @inheritDoc
 	 */
-	public function setLatestChildDateTime(\DateTime $dateTime = null) {
+	public function setLatestChildDateTime(?\DateTime $dateTime = null) {
 		$this->data['latestChildDT'] = $dateTime;
 		return $this;
 	}
diff --git a/lib/private/Comments/Manager.php b/lib/private/Comments/Manager.php
index 50b5fabc6a2..b82df1bccc8 100644
--- a/lib/private/Comments/Manager.php
+++ b/lib/private/Comments/Manager.php
@@ -170,7 +170,6 @@ class Manager implements ICommentsManager {
 
 		if ($comment->getId() === '') {
 			$comment->setChildrenCount(0);
-			$comment->setLatestChildDateTime(new \DateTime('0000-00-00 00:00:00', new \DateTimeZone('UTC')));
 			$comment->setLatestChildDateTime(null);
 		}
 
diff --git a/lib/public/Comments/IComment.php b/lib/public/Comments/IComment.php
index 44d294bb07c..eb696fa5f06 100644
--- a/lib/public/Comments/IComment.php
+++ b/lib/public/Comments/IComment.php
@@ -230,11 +230,11 @@ interface IComment {
 	/**
 	 * sets the date of the most recent child
 	 *
-	 * @param \DateTime $dateTime
+	 * @param \DateTime|null $dateTime
 	 * @return IComment
 	 * @since 9.0.0
 	 */
-	public function setLatestChildDateTime(\DateTime $dateTime);
+	public function setLatestChildDateTime(?\DateTime $dateTime = null);
 
 	/**
 	 * returns the object type the comment is attached to