The 27-year-old, who joined the Scottish outfit from Middlesbrough in 2011, has emerged into a key player for the club this season.
However, with his current deal set to expire at the end of the season, McNamara has confirmed that he is planning talks to extend Flood's contract.
He told the Daily Record: "Willo has been excellent in the past two games. Of course, I would like to keep him longer come the end of the season.
"I will sit down with the chairman and Willo's future will be on the agenda, along with that of a few others."
Flood has also played for Cardiff City.