Brandon Hanlan's fifth goal of the season gave Gillingham a late 1-0 victory over fellow strugglers Oxford.
Hanlan bundled the ball home from close range after Max Ehmer diverted Callum Reilly's deep corner into his path in the 89th minute to send Steve Lovell's men up to 14th.
Gills striker Tom Eaves had earlier missed his third penalty of the season, with goalkeeper Simon Eastwood saving well following Rob Dickie's clumsy foul on Hanlan.
The visitors, who slipped into the relegation zone after this defeat, felt they should have been awarded a penalty two minutes after the hosts' when goalkeeper Tomas Holy appeared to shove Jerome Sinclair.
Looking to claim three league wins in a row for the first time since October 2017, Oxford came close to scoring when Holy made a brilliant fingertip save to push Jordan Graham's effort over the crossbar 15 minutes from time.
Luke Garbutt fired inches wide after a driving run through midfield and Gavin Whyte miscued his shot after rushing to meet Sinclair's delivery across the face of goal late on.