The Scottish Under-21 international showed his reactions to keep out Scott Doe's point-blank effort in the second half as Wycombe held onto their lead from Sam Wood's strike on the half-hour.
The victory and another clean sheet helped the Chairboys move 10 points clear of the relegation zone with just two defeats in the last 10.
Adam Smith played 90 minutes as Millwall suffered a 2-0 loss at home to Burnley in the Championship. The full-back has now started 16 matches for the Lions, who are five points outside the play-offs.
In the Premier League, Harry Kane was an unused substitute as Norwich City were hammered 5-0 at Anfield while Danny Rose was ruled out of Sunderland's win at Wigan through injury.