diff --git a/wp-includes/class-wp-roles.php b/wp-includes/class-wp-roles.php
index ff733e2206..916a54c05c 100644
--- a/wp-includes/class-wp-roles.php
+++ b/wp-includes/class-wp-roles.php
@@ -69,12 +69,21 @@ class WP_Roles {
 	 */
 	public $use_db = true;
 
+	/**
+	 * @since 4.7.0
+	 * @access protected
+	 * @var wpdb
+	 */
+	protected $db;
+
 	/**
 	 * Constructor
 	 *
 	 * @since 2.0.0
 	 */
 	public function __construct() {
+		$this->db = $GLOBALS['wpdb'];
+
 		$this->_init();
 	}
 
@@ -105,12 +114,11 @@ class WP_Roles {
 	 * @since 2.1.0
 	 * @access protected
 	 *
-	 * @global wpdb  $wpdb          WordPress database abstraction object.
 	 * @global array $wp_user_roles Used to set the 'roles' property value.
 	 */
 	protected function _init() {
-		global $wpdb, $wp_user_roles;
-		$this->role_key = $wpdb->get_blog_prefix() . 'user_roles';
+		global $wp_user_roles;
+		$this->role_key = $this->db->get_blog_prefix() . 'user_roles';
 		if ( ! empty( $wp_user_roles ) ) {
 			$this->roles = $wp_user_roles;
 			$this->use_db = false;
@@ -137,18 +145,15 @@ class WP_Roles {
 	 *
 	 * @since 3.5.0
 	 * @access public
-	 *
-	 * @global wpdb $wpdb WordPress database abstraction object.
 	 */
 	public function reinit() {
 		// There is no need to reinit if using the wp_user_roles global.
-		if ( ! $this->use_db )
+		if ( ! $this->use_db ) {
 			return;
-
-		global $wpdb;
+		}
 
 		// Duplicated from _init() to avoid an extra function call.
-		$this->role_key = $wpdb->get_blog_prefix() . 'user_roles';
+		$this->role_key = $this->db->get_blog_prefix() . 'user_roles';
 		$this->roles = get_option( $this->role_key );
 		if ( empty( $this->roles ) )
 			return;
diff --git a/wp-includes/version.php b/wp-includes/version.php
index e82c435824..9d192d3797 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.7-alpha-38386';
+$wp_version = '4.7-alpha-38387';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.