Millen made two signings on transfer deadline day, a 93-day loan deal for Wolves striker Andy Keogh and a permanent swoop for Scunthorpe`s Martyn Woolford.
However, he still feels his squad is lacking in certain areas, particularly in defence and midfield.
"If we feel the right person is out there and available then we will act," Millen told the club`s official website.
"If there are one or two players available to get in on loan then I`m sure the chairman will be happy to do that.
"We`re a bit short in defence and with injuries we are also short in midfield. We only want people who will improve the squad though, possibly with long-term deals in mind."
Source: PA
Source: PA