Wallace and his Gers team-mates maintained their 23-point lead at the top of the league table at the weekend. But they struggled to beat Brechin City 2-1 at Ibrox on Saturday after Bilel Mohsni was sent off in the second half.
It was the second time in eight days that Ally McCoist's side had laboured to defeat part-time opposition at home, and Wallace would like to see a big improvement - starting in the William Hill Scottish Cup game against Dunfermline on Friday night.
He said: "I don't think we have have allowed ourselves to become complacent because of the lead we have in the league at the moment.
"I just think it has just been down to a general slackness on the pitch.
"Even when Bilel had been sent off on Saturday, we still had 10 men on the park who were more than capable of seeing the game out, which we did do … But we could have gone on and scored more goals with 10 men.
"It was disappointing we didn't. It didn't really feel like a victory."
Wallace added: "That is a result of the standard that we have set. We want to win games, we want to win them well, we want to play well.
"We know the reaction that we are going to get from the fans if we don't win the games comfortably."
Sky Bet Championship club Nottingham Forest made two bids for Wallace last week before the January transfer window closed.
The 26-year-old, who stayed with Rangers after they were put into the bottom tier last season, was delighted the offers were rejected.
He said: "We have a title to wrap up, the Ramsdens Cup final to look forward to and a Scottish Cup game we want to do well in this week.
"We are nearing the second stage of our recovery as a club. I am more than happy to be part of that and I have said on a number of occasions that I will be here for a long time."
Rangers will be without first-choice centre-backs, captain Lee McCulloch and Mohsni, for the league game with Ayr at Somerset Park on Saturday week.
McCulloch picked up his sixth booking of the season against Brechin. Mohsni was sent off for a second bookable offence.