diff --git a/wp-admin/includes/user.php b/wp-admin/includes/user.php
index 5883703235..2e59b552ca 100644
--- a/wp-admin/includes/user.php
+++ b/wp-admin/includes/user.php
@@ -66,7 +66,7 @@ function edit_user( $user_id = 0 ) {
 	}
 
 	if ( !$update && isset( $_POST['user_login'] ) )
-		$user->user_login = sanitize_user($userdata['user_login'], true);
+		$user->user_login = sanitize_user($_POST['user_login'], true);
 
 	$pass1 = $pass2 = '';
 	if ( isset( $_POST['pass1'] ))