Database Error!

Error: Field 'last_seen' doesn't have a default value
Query: INSERT INTO users (uid, password, ip_address, first_seen) VALUES ("5c6d68be842149.58464391", "USFm8h2BKdUmO1ZkWNtg1LBM4tlSNklQ", "18.206.175.155", UNIX_TIMESTAMP())
File: /includes/database.class.php
Line: 98
Backtrace: