diff --git a/wp-includes/user.php b/wp-includes/user.php
index 76fd6afeb9..483b3bccfd 100644
--- a/wp-includes/user.php
+++ b/wp-includes/user.php
@@ -85,7 +85,7 @@ function wp_authenticate_username_password($user, $username, $password) {
 
 	$userdata = get_userdatabylogin($username);
 
-	if ( !$userdata || ($userdata->user_login != $username) ) {
+	if ( !$userdata ) {
 		return new WP_Error('invalid_username', sprintf(__('<strong>ERROR</strong>: Invalid username. <a href="%s" title="Password Lost and Found">Lost your password</a>?'), site_url('wp-login.php?action=lostpassword', 'login')));
 	}