diff --git a/src/wp-includes/class-wp-comment.php b/src/wp-includes/class-wp-comment.php
index c5a0bd9aaf..b42523da37 100644
--- a/src/wp-includes/class-wp-comment.php
+++ b/src/wp-includes/class-wp-comment.php
@@ -33,7 +33,7 @@ final class WP_Comment {
 	 * @since 4.4.0
 	 * @var string
 	 */
-	public $comment_post_ID = 0;
+	public $comment_post_ID = '0';
 
 	/**
 	 * Comment author name.
@@ -99,7 +99,7 @@ final class WP_Comment {
 	 * @since 4.4.0
 	 * @var string
 	 */
-	public $comment_karma = 0;
+	public $comment_karma = '0';
 
 	/**
 	 * Comment approval status.
@@ -134,7 +134,7 @@ final class WP_Comment {
 	 * @since 4.4.0
 	 * @var string
 	 */
-	public $comment_parent = 0;
+	public $comment_parent = '0';
 
 	/**
 	 * Comment author ID.
@@ -144,7 +144,7 @@ final class WP_Comment {
 	 * @since 4.4.0
 	 * @var string
 	 */
-	public $user_id = 0;
+	public $user_id = '0';
 
 	/**
 	 * Comment children.