The Dutch centre-back may be forced straight into the starting XI, giving Ian Baraclough a rest from the side.
Tony Mowbray's side signed Martis from Scottish side Hibernian in a £50,000 deal in the summer, having previously worked with Mowbray at Easter Road.
"Opportunities have been hard to come by for Shelton here so far but I particularly like his qualities," explained Mowbray.