Michel Vorm has bid farewell to the 'Swansea family' after completing his move to Premier League rivals Tottenham.
Nigel Pearson is hoping to further bolster his ranks at Leicester and says he has no intention of letting anyone leave.
The 22-year-old, a former France Under-21 international, was given the all clear to switch to the French club following an approach before the transfer deadline.
Gueye, who moved to Goodison Park from Strasbourg in June 2010, has made just six appearances for the Toffees this season.
Brest are currently only four points above the Ligue 1 relegation zone.