Index: wp-includes/user.php
===================================================================
--- wp-includes/user.php	(revision 12462)
+++ wp-includes/user.php	(working copy)
@@ -638,9 +638,8 @@
 		else
 			$vars = get_object_vars($user);
 		foreach ( array_keys($vars) as $field ) {
-			if ( is_array($user->$field) )
-				continue;
-			$user->$field = sanitize_user_field($field, $user->$field, $user->ID, $context);
+			if ( is_string($user->$field) || is_numeric($user->$field) )
+				$user->$field = sanitize_user_field($field, $user->$field, $user->ID, $context);
 		}
 		$user->filter = $context;
 	} else {