Millen ends Bristol City's foray into the transfer market
"I will be surprised now if any other players come in, I'm not actively looking," he told City's official website.
"To be honest I'm very conscious of the need to settle things down after all the upheaval here.
"Ever since July 1, when we returned for training, it's been a really difficult period for the club, both behind the scenes and in the transfer market.
"Now is the time to settle everything down. This is a new group of players and, although it may take a little bit of time, they need to gel quickly."