Bristol have signed former Wales scrum-half Martin Roberts from Pro12 side Ospreys until the end of next season.
The 29-year-old won three international caps in 2008 and 2009.
With Dwayne Peel and Andy Uren sidelined through injury, Roberts will be competing with Will Cliff, Craig Hampson and Will Homer for the scrum-half jersey.
"He's a dynamic scrum half and a strong communicator," said Bristol's director of rugby Andy Robinson.
Roberts added: "There's a big second half of the season to come and then the play-offs, so I'm looking forward to working hard and contributing to the squad."
Meanwhile Premiership side Worcester, who defeated Bristol in the Championship play-off final last season, have signed 24-year-old back row Marco Mama on a permanent deal.
Mama has made 12 appearances for the club since joining Warriors on loan in August.