A change in policy for the Leadville Trail 100, a 100-mile footrace through the rugged Colorado Rockies, has made it harder for runners attempting the famed grand slam of ultrarunning—completing Western States, the Leadville 100, Vermont, and Wasatch all in the same summer.

Leadville 100 race director Paul Anderson announced last week that aspiring Grand Slam runners will no longer receive automatic entry into Leadville.

The Grand Slam was conceived by pioneer ultrarunner, Tom Green, who strung together the four famous 100 miles races together in a single summer. Since then, around 300 people have accomplished the grueling feat.

Paul Anderson, current race director of the Leadville 100, said they made the switch to the lottery system because he found it unfair to give people priority for an “unofficial event.” However, Anderson said he would like to give priority to people who have volunteered in past Leadville 100 races. Any grand slam aspirants should consider volunteering at future races to increase their chance of getting into Leadville.