diff --git a/user_guide/libraries/sessions.html b/user_guide/libraries/sessions.html
index 78049d2..9a2ca93 100644
--- a/user_guide/libraries/sessions.html
+++ b/user_guide/libraries/sessions.html
@@ -202,7 +202,7 @@
 ip_address varchar(16) DEFAULT '0' NOT NULL,
 user_agent varchar(50) NOT NULL,
 last_activity int(10) unsigned DEFAULT 0 NOT NULL,
-user_data text NOT NULL,
+user_data text DEFAULT '' NOT NULL,
 PRIMARY KEY (session_id)
 );</textarea>