Colchester manager Joe Dunne was disappointed with both goals conceded in the 2-0 home defeat to Notts County.
First-half goals from Neal Bishop and Alan Judge gave the Magpies their fifth away win of the season and lifted them up to fifth in League One.
"We set our stall out to get after them and we did that," said Dunne. "We attacked them and got balls into the box and into good positions.
"But again it was our old bad habit of conceding from set-pieces and giving away stupid free-kicks in wrong areas that cost us and I probably now need to look at changing things. We conceded two very disappointing goals.
"Somebody should have been marking Neal Bishop for his goal - I won't name who it is. That's happened before and we didn't deal with the second goal.
"I've asked my team to pass it and they need to stick with what we're trying to do because I thought that in the second half we were bright enough. We moved the ball around and we can't be criticised for our lack of effort."