The only goal of the game came in the 33rd minute against the run of play.
Derry cleared a ball out of their box and it fell to fullback Mark Langtry who smashed a great drive beyond the Derry keeper from 25 yards.
Derry did make some chances and Seam Houston should have equalised with a header from two yards out having met a Dean Jarvis cross from the left on the stroke of halftime.
Derry end the league campaign away to Bohemians next Friday.
After the game a disappointed Derry boss Peter Hutton gave his reaction to Martin Holmes.