Database Error!

Error: Field 'last_seen' doesn't have a default value
Query: INSERT INTO users (uid, password, ip_address, first_seen) VALUES ("5c9a9f54ac6061.69209075", "zIMtrXm3OdWoa6QgmRlW1HX9aTNYnL6q", "54.242.115.55", UNIX_TIMESTAMP())
File: /includes/database.class.php
Line: 98
Backtrace: