Lockwood, 28, has started all eight league games and two Carling Cup ties for Sean O'Driscoll's side this season, with all but one of the Championship matches being alongside Shackell, on loan from Wolves until January.
Lockwood said: "It's going okay alongside Jason. He's a good defender and we've kept a few clean sheets already and that gives you confidence.
"But we've conceded a few in recent games and we're always trying to improve.
"It could have been better against Ipswich, but with a lot of hard work I'm sure we can keep a few more clean sheets."