The 22 year old Scotsman came through his first full 90 minutes for the Imps in the 2-1 Boxing Day win over Chesterfield, and despite having only two other appearances to his name has convinced the management that he is worth an extra five months.
Gilmour started his career at Rangers before playing for both Clyde and Queen of the South in Scotland. He spent an unhappy spell in Finland before being snapped up by Chris Sutton prior to the FA Cup win over Northwich. He made his Imps debut in that televised game, as did Villa loanee Chris Herd.
Gilmour has represented Scotland from Under 13 to Under 20 level and will be looking to use the next five months to earn himself a lengthier deal in the summer.