The controversial aggregate qualifying system introduced for this year's World Endurance Championship has been tweaked with immediate effect.
The principles of the system, by which the grid is determined by the average time of four laps set by two drivers in each car, remain intact, but the length of the sessions has been increased.
The length of the two sessions, one for the LMP1 and LMP2 and one for GTE Pro and Am, has been increased by five minutes. That means the sessions will now be 25 rather than 20 minutes and, on the four-mile Spa circuit this weekend, 30 rather than 25 minutes.
Vincent Beaumesnil, sporting manager of the WEC promoter the Automobile Club de l'Ouest, said: "We saw what happened at Silverstone [the first round of the series] and decided that five minutes more is better on safety grounds because it puts less pressure on the teams."
Further changes to the system, which received widespread criticism from teams and drivers at Silverstone, have been ruled out for the remainder of the season.
WEC series boss Gerard Neveu said: "We need to see the system working through the whole season and then make any changes."
Neveu and Beamesnil promised that the computer problems that resulted in the results of qualifying at Silverstone being published an hour after the sessions have been fixed for Spa.
The system will not be used at the Le Mans 24 Hours round of the WEC next month because there are three qualifying sessions each of two hours on the Wednesday and Thursday of race week.