diff --git a/trunk/install/update.sql b/trunk/install/update.sql
index 4cfde1b1bdc..7924ea95a0f 100644
--- a/trunk/install/update.sql
+++ b/trunk/install/update.sql
@@ -29,6 +29,7 @@ alter table users add column starred int default 0 after activecode ;
 alter table users add column expiry_date date not null default '2099-01-01' after reg_time;
 alter table contest add column contest_type tinyint UNSIGNED default 0 after `password`;
 alter table contest add column subnet varchar(255) not null default '' after contest_type;
+alter table online modify refer varchar(4096) DEFAULT NULL;
 #create fulltext index problem_title_source_index on problem(title,source);