First Division leaders Morton maintained their two-point advantage over Partick Thistle with victory at Dumbarton.
Michael Tidser unleashed a left-foot strike from 25 yards to give the visitors the lead.
Martin Hardie's header doubled Morton's tally before the break.
And Peter MacDonald completed the scoring near the end, nodding home Colin McMenamin's cross.
Dumbarton: Grindlay, McGinn, Graham, Lithgow, Smith, Gilhaney, Turner (Phinn 68), Agnew, McDougall, Prunty (Winters 56), Fleming. Subs Not Used: Ewings, Lamont, Urquhart.
Booked: Fleming, Lithgow.
Morton: Gaston, Taggart, Rutkiewicz, Reid, O'Ware, Bachirou, Hardie, Tidser (Wallace 82), Wilkie (Halsman 80), Campbell (McMenamin 64), MacDonald. Subs Not Used: Hutton, Weatherson.
Goals: Tidser 32, Hardie 38, MacDonald 81.
Ref: Paul Robertson