The Boro head coach saw Leicester striker David Nugent added to the mix last week to cap a good recruitment drive and a promising start to the new Championship campaign.
Karanka told the club’s official website: “We are working, but as I’ve said before, if the transfer deadline was tomorrow, I am happy with my squad.
“If someone does come in, it will because we want them and they want to be here.”
Karanka has studiously avoided discussing the men on his wish-list amid persistent links with Blackburn striker Jordan Rhodes, and was refusing to do so again as speculation continued over Nottingham Forest winger Michail Antonio.
He said: “Everybody spoke about our link with Jordan Rhodes and he’s not here.
“People thought we were signing Rhodes and [Crystal Palace striker Dwight] Gayle…but I’d rather not talk about players who aren’t here. I’d rather talk about the players who are here.”