Database Error!

Error: Field 'last_seen' doesn't have a default value
Query: INSERT INTO users (uid, password, ip_address, first_seen) VALUES ("5d59d8492dea26.67661393", "09iok5x3SVHSVZoxFZvAXy1MAVhCPqfT", "35.173.48.224", UNIX_TIMESTAMP())
File: /includes/database.class.php
Line: 98
Backtrace: