Database Error!

Error: Field 'last_seen' doesn't have a default value
Query: INSERT INTO users (uid, password, ip_address, first_seen) VALUES ("5d59d939cfd722.89954053", "QH0SarXg9FANaMZRkdS9lNXON4kVmPaG", "35.173.48.224", UNIX_TIMESTAMP())
File: /includes/database.class.php
Line: 98
Backtrace: