Index: wp-includes/user.php
===================================================================
--- wp-includes/user.php	(revision 15541)
+++ wp-includes/user.php	(working copy)
@@ -355,6 +355,10 @@
 	var $query_orderby;
 	var $query_limit;
 
+	function WP_User_Query( $query = null ) {
+		return $this->__construct( $query );
+	}
+
 	/**
 	 * Sets up the object properties.
 	 *
@@ -363,18 +367,20 @@
 	 * @param string|array $args The query variables
 	 * @return WP_User_Query
 	 */
-	function WP_User_Query( $query ) {
-		$this->query_vars = wp_parse_args( $query, array(
-			'search' => '', 'role' => '',
-			'offset' => '', 'number' => '', 'count_total' => true,
-			'orderby' => 'login', 'order' => 'ASC',
-			'meta_key' => '', 'meta_value' => '',
-			'include' => array(), 'exclude' => array(),
-			'fields' => 'all'
-		) );
+	function __construct( $query = null ) {
+		if ( ! empty( $query ) ) {
+			$this->query_vars = wp_parse_args( $query, array(
+				'search' => '', 'role' => '',
+				'offset' => '', 'number' => '', 'count_total' => true,
+				'orderby' => 'login', 'order' => 'ASC',
+				'meta_key' => '', 'meta_value' => '',
+				'include' => array(), 'exclude' => array(),
+				'fields' => 'all'
+			) );
 
-		$this->prepare_query();
-		$this->query();
+			$this->prepare_query();
+			$this->query();
+		}
 	}
 
 	/**