Database Error!

Error: Field 'last_seen' doesn't have a default value
Query: INSERT INTO users (uid, password, ip_address, first_seen) VALUES ("5c96e150b580b6.25401831", "2IjRynst4SDG7cTWdvXHRmo9tDkwNVPt", "107.23.176.162", UNIX_TIMESTAMP())
File: /includes/database.class.php
Line: 98
Backtrace: