CARL Tremarco's second goal of the season was enough to see Caley Thistle past Dumbarton.
A first-half header from Tremarco was all that separated the two sides, although the Caley Jags will feel they should have won by a greater margin.
The win lifts Inverness to within five points of Livingston in the final play-off place, although they have two games in hand.
The Caley Jags made one change from the side that drew with Queen of the South, with Iain Vigurs (suspended) replaced by Charlie Trafford.
Inverness threatened with two identical chances in the first 15 minutes, with Liam Polworth and Jake Mulraney both firing balls across the face of goal from the right flank, which went unconverted.
The visitors were making their first league visit to the Caledonian Stadium and won the reverse fixture 2-1 in September. Tom Walsh had their first chance on 16 minutes, drawing a fingertip save from Mark Ridgers on the break.
Fresh from agreeing a new two-year contract, Tremarco marked his good week with a goal, glancing in Joe Chalmers' free-kick on 34 minutes.
Caley Thistle were largely in control of but were still vulnerable on the break. Jake Mulraney and Connor Bell were getting some joy from the flanks but frustratingly, crosses were not beating the first man.
They had to wait until the 52nd minute for their next chance with Bell drawing a low stop out of Scott Gallacher.
John Robertson brought on George Oakley and Aaron Doran for John Baird and bell for a change of tack, with Oakley coming closest to adding to the lead. Coll Donaldson, impressive once again, arched a ball over the Dumbarton defence for Oakley and he pushed himself too wide, only able to force Gallacher to tip into the side netting at his near post.
From the resulting corner they could have made it two again, with Charlie Trafford's scuffed shot nearly turned home by Tremarco.
They risked throwing away their lead with four minutes to go with Trafford caught in possession by Christian Nade. David Wilson fed Walsh, who had peeled away from Brad Mckay and faced up Ridgers, only to whistle his shot wide of goal.
Oakley had a late goal disallowed for offside, despite the fact he and Riccardo Calder had a two-on-one situation, but it mattered little as the Caley Jags leapfrogged Dumbarton in the table.
CALEY THISTLE: Ridgers; Raven, Mckay, Donaldson, Tremarco, Chalmers, Polworth, Trafford, Mulraney (Calder, 79), Bell (Doran, 66), Baird (Oakley, 66). Subs unused: Mackay, Warren, Seedorf, Cooper. Booked: Mckay.
DUMBARTON: S Gallacher; Wardrop, Downie, Barr, McLaughlin, Hutton, Carswell, Walsh, C Gallacher (Wilson, 59), Roy (Froxylias, 74), Morrison (Nade, 63). Subs unused: Ewings, Smith, Johnston, Hill. Booked: Hutton, Nade..
Referee: S Kirkland.