diff --git a/wp-includes/nav-menu-template.php b/wp-includes/nav-menu-template.php
index 1dfc6616d3..4b9293b1d1 100644
--- a/wp-includes/nav-menu-template.php
+++ b/wp-includes/nav-menu-template.php
@@ -74,10 +74,10 @@ class Walker_Nav_Menu extends Walker {
 		$classes[] = 'menu-item-' . $item->ID;
 
 		$class_names = join( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item, $args ) );
-		$class_names = ' class="' . esc_attr( $class_names ) . '"';
+		$class_names = $class_names ? ' class="' . esc_attr( $class_names ) . '"' : '';
 
 		$id = apply_filters( 'nav_menu_item_id', 'menu-item-'. $item->ID, $item, $args );
-		$id = strlen( $id ) ? ' id="' . esc_attr( $id ) . '"' : '';
+		$id = $id ? ' id="' . esc_attr( $id ) . '"' : '';
 
 		$output .= $indent . '<li' . $id . $value . $class_names .'>';