The Liverpool boss says Everton are a threat from set-pieces, as they showed on Monday, and so the players must avoid giving away silly free-kicks in dangerous areas.
"We have talked about both things. We had to be careful and not commit silly fouls, and then after we had to defend the set piece," said Benitez.
"Okay, we made the mistake and maybe we can learn from it for the future.
"Clearly we have talked about this. The players realise that we have to improve. But we are not conceding too many goals and it is always going to seem worse when you concede such an important goal in a derby.
"We work on these things every week, practicing set pieces for and against."
