The Black Cats kept as many as 13 clean sheets in the Premier League last season and managed to retain their English top-flight status.
So far this campaign, Sunderland have kept just two shut-outs in the league, and Allardyce believes that this is the area in which his team need to improve.
“We have to stop the goals going in,” the former Newcastle United and West Ham United manager told The Sunderland Echo.
“The only games we’ve won, we kept clean sheets. Last season, they stayed up with a team that hardly scored a goal, but they got 13 clean sheets.
"The two leading goalscorers were on five, which were Connor Wickham and Steven Fletcher. It was the 13 clean sheets which kept them up.
“I think we’ve got more goals this year. In fact, Steven Fletcher and Jermain Defoe have already scored four. If we sort the goals against out, we’ll stay up because there’s goals in the team.”
Just like last season, Sunderland are struggling for survival in the Premier League this campaign.
The Black Cats are third from bottom in the league table at the moment with nine points from 13 matches, just a point behind 17th-place Newcastle United.
Bournemouth and Aston Villa make up the bottom three in the standings, while Norwich City are just three points above the relegation zone.
Sunderland will take on Stoke City at the Stadium of Light in the Premier League on Saturday afternoon.