Scrum-half Rory Kockott has committed his future to Castres, with the French champions announcing that he had signed a new three-year deal.
The 27-year-old had signed a pre-contract agreement with Toulon but indicated earlier this month that he had changed his mind and wished to stay at Castres.
"It is taken a while to finalise but we needed to be sure all the conditions were met before we came to an agreement that was acceptable for all parties," said Castres manager Matthias Rolland.
Kockott, who joined Castres in June 2011, is now tied to the club until the summer of 2017.
The move means Castres will be obliged to pay Toulon between a reported 300-400,000 euros ($410,000-540,000) in compensation.