Advocates for injured workers are raising awareness about changes to their benefit policies, when the Workplace Safety and Insurance Board rolls out changes next month.

There's concern the revisions could affect a worker's eligibility to file claims.

Demonstrators rallied in the rain in downtown Sudbury on Thursday, arming themselves with colourful signs to protest workers' compensation changes.

"To me, it's a war. Nothing clean about it,” said Herne Steelegrave, who came from Manitoulin Island to show his support.

He's worried about a new policy that considers pre-existing injuries.

"They've got every knee scrape and concussion that you got when you were a crazy kid on a bike. And suddenly all these things are held against you."

Kate Lamb with Workplace Safety and Insurance Board said that won’t be the case.

"The existence of a pre-existing condition would not prevent a worker from receiving benefits,” she said.

But the demonstrators say they don't interpret the policy that way.

Colin Pick, a retired Sudbury police officer who was injured on the job 26 years ago, said the changes will make it harder for workers to make claims.

“Once these polices are imposed in total … it's taking away from what was there and leaving nothing in its place.”

More changes are on the way for worker's compensation, as the WSIB says it intends to update all of its policies.