Stoke have exercised their right to buy defender Philipp Wollscheid from Bayer Leverkusen after a successful loan deal.
The 26-year-old has made 14 appearances for the Potters since joining in January.
Stoke announced Wollscheid has signed a three-year deal after the club paid an undisclosed fee to Leverkusen.
Stoke chief executive Tony Scholes said on the club's website: "We're delighted to have secured Philipp's services on a permanent basis. He joined us midway through the season but wasted little...