Wasps have completed the signing of Glasgow Warriors centre James Downey, as well as bringing in three other new faces for next season.
They have also signed Leinster centre Brendan Macken, 24, who spent part of this season on loan with Gloucester.
Prop Tom Bristow, 23, will join from Leicester, along with London Scottish scrum-half Jamie Stevenson, also 23.
Experienced once-capped Irish international Downey, 34, first arrived in February as injury cover.
He was part of the Northampton Saints squad that won promotion to the Premiership in 2008.
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"The depth of your squad is extremely important," said Wasps director of rugby Dai Young.
"You need high quality cover for injuries and to be able to rest players when they need it during the year, managing the squad to arrive at the business end of the season in the best shape possible.
"We have three talented, young players coming in in Brendan Macken, Tom Bristow and Jamie Stevenson, and I'm also pleased that James Downey will be staying next season - his experience at the top level has been really beneficial."
After four seasons at London Scottish, Scotland A scrum-half Stevenson will link up at Wasps with former Whitgift School team mate Elliot Daly, who was this week named in England's 50-man World Cup training squad.
Ireland Under-20s international Macken has spent five seasons with his provincial side Leinster, while Bristow arrives after two seasons at Welford Road, prior to which he made 21 appearances for London Welsh.