diff --git a/wp-includes/class-wp-walker.php b/wp-includes/class-wp-walker.php
index c5e3b5129b..1ef489949a 100644
--- a/wp-includes/class-wp-walker.php
+++ b/wp-includes/class-wp-walker.php
@@ -39,6 +39,15 @@ class Walker {
 	 */
 	protected $max_pages = 1;
 
+	/**
+	 * Wether the current element has children or not. To be used in start_el()
+	 *
+	 * @since 4.0.0
+	 * @var bool
+	 * @access protected
+	 */
+	protected $has_children;
+
 	/**
 	 * Make private properties readable for backwards compatibility
 	 *
@@ -172,15 +181,17 @@ class Walker {
 			return;
 
 		$id_field = $this->db_fields['id'];
+		$id       = $element->$id_field;
 
 		//display this element
-		if ( isset( $args[0] ) && is_array( $args[0] ) )
-			$args[0]['has_children'] = ! empty( $children_elements[$element->$id_field] );
+		$this->has_children = ! empty( $children_elements[ $id ] );
+		if ( isset( $args[0] ) && is_array( $args[0] ) ) {
+			$args[0]['has_children'] = $this->has_children; // Backwards compatibility.
+		}
+
 		$cb_args = array_merge( array(&$output, $element, $depth), $args);
 		call_user_func_array(array($this, 'start_el'), $cb_args);
 
-		$id = $element->$id_field;
-
 		// descend only when the depth is right and there are childrens for this element
 		if ( ($max_depth == 0 || $max_depth > $depth+1 ) && isset( $children_elements[$id]) ) {
 
diff --git a/wp-includes/comment-template.php b/wp-includes/comment-template.php
index b905be0ec4..b3b1e2e781 100644
--- a/wp-includes/comment-template.php
+++ b/wp-includes/comment-template.php
@@ -1784,7 +1784,7 @@ class Walker_Comment extends Walker {
 			$add_below = 'div-comment';
 		}
 ?>
-		<<?php echo $tag; ?> <?php comment_class( empty( $args['has_children'] ) ? '' : 'parent' ); ?> id="comment-<?php comment_ID(); ?>">
+		<<?php echo $tag; ?> <?php comment_class( $this->has_children ? 'parent' : '' ); ?> id="comment-<?php comment_ID(); ?>">
 		<?php if ( 'div' != $args['style'] ) : ?>
 		<div id="div-comment-<?php comment_ID(); ?>" class="comment-body">
 		<?php endif; ?>
@@ -1830,7 +1830,7 @@ class Walker_Comment extends Walker {
 	protected function html5_comment( $comment, $depth, $args ) {
 		$tag = ( 'div' === $args['style'] ) ? 'div' : 'li';
 ?>
-		<<?php echo $tag; ?> id="comment-<?php comment_ID(); ?>" <?php comment_class( empty( $args['has_children'] ) ? '' : 'parent' ); ?>>
+		<<?php echo $tag; ?> id="comment-<?php comment_ID(); ?>" <?php comment_class( $this->has_children ? 'parent' : '' ); ?>>
 			<article id="div-comment-<?php comment_ID(); ?>" class="comment-body">
 				<footer class="comment-meta">
 					<div class="comment-author vcard">