Players’ union executives from the NFL, NBA, MLB and NHL have had several formal meetings to begin preparing for a potential legalization of sports gambling, NFLPA executive George Atallah told The MMQB on Thursday.

The representatives have been meeting over the past year and a half to discuss the impact that legalized sports gambling could have on players, the MMQB report said.

“Yes, the sports unions have been discussing the issue, in particular around the integrity of our respective games,” Atallah told The MMQB. “We’re collaborating on it. We might be open to changes that are coming because of [legalized sports gambling], but before we get to the revenue aspect of it, do we have the infrastructure in place to prevent any sort of shenanigans? That’s the issue.”

Atallah told the MMQB that the players’ unions have looked into how overseas countries have handled legalized sports gambling. They have also looked at legislation in New Jersey, where efforts to legalize sports betting have been made for several years.

ESPN has reached out to the NBPA and NFLPA for comment.