Middlesex pace bowler James Harris has signed a new two-year contract.
The 25-year-old, who joined from Glamorgan in 2013, is currently the second highest wicket-taker in first-class cricket this season, with 36 at an average of 21.55 runs.
And the Welshman's deal will be automatically extended to 2018 "once an agreed set of criteria have been reached", the club have announced.
"I am thrilled to have signed an extension to my contract," he said.
"I've been really pleased with my form in the early part of this season and am looking forward to this continuing for Middlesex for the remainder of this season and in years to come."
Harris has played for the England Lions team, but has yet to graduate to the senior side despite taking 308 first-class wickets during his career.
Middlesex's managing director of cricket Angus Fraser said: "There have been a few counties showing interest in him, so I am delighted he has committed his immediate future to us.
"The great thing is that he still only 25 and has many years in the game to look forward to. We believe he has the potential to become a high-quality all-rounder."