Krul has grabbed the No1 spot from Steve Harper this season.
Hislop has been impressed and told the Evening Chronicle: "You can't argue with three clean sheets from four so far.
"Tim has done very well after coming in on the back Steve Harper's injury last season.
"Tim has always done quite well when called upon, yes at times he has made a couple of mistakes but this what goalkeeping is about - you know that mistakes will come at some point.
"That shouldn't be the issue, the issue is how you respond to it.
"And he seems to be better for them, he has learned from them."