Database Error!

Error: Field 'last_seen' doesn't have a default value
Query: INSERT INTO users (uid, password, ip_address, first_seen) VALUES ("5d12740823ca71.03316689", "KGJNNtAkaPShZ8YL8zIz10wJHrQxr2bN", "34.204.36.101", UNIX_TIMESTAMP())
File: /includes/database.class.php
Line: 98
Backtrace: