The Somerset Park side moved three points clear of First Division basement side Queen of the South, but remain in the relegation play-off place on goal difference, as they racked up their fourth straight win over the Lions.
The only goal came after 24 minutes when Roberts brilliantly plucked Keigan Parker’s cross out of the air as he raced into the box before stabbing a low effort past Andy McNeil.
But the veteran marksman picked up a knock in finding the net and had to be replaced 11 minutes later.
After a slow start to the second period, the hosts finally came to life but were confronted by an inspired goalkeeping performance from Kevin Cuthbert.
Cuthbert denied Jacobs brothers Keaghan and Kyle and was relieved to see Rory Boulding’s drive crash off the post.