diff --git a/src/wp-includes/class-wp-comment-query.php b/src/wp-includes/class-wp-comment-query.php
index 573115a952..a4429c97ec 100644
--- a/src/wp-includes/class-wp-comment-query.php
+++ b/src/wp-includes/class-wp-comment-query.php
@@ -1020,10 +1020,7 @@ class WP_Comment_Query {
 
 		// Prime comment caches for non-top-level comments.
 		$descendant_ids = array();
-		for ( $i = 1, $c = count( $levels ); $i <= $c; $i++ ) {
-			if ( empty( $levels[ $i ] ) ) {
-				continue;
-			}
+		for ( $i = 1, $c = count( $levels ); $i < $c; $i++ ) {
 			$descendant_ids = array_merge( $descendant_ids, $levels[ $i ] );
 		}