GREEN BAY, Wis. (AP) — A prisoner advocacy group says a northeastern Wisconsin prison is battling an ongoing mice infestation.

Dant’e Cottingham, interim associate director of Ex-Incarcerated People Organizing, says prisoners at the Green Bay Correctional Institution are placing rolled-up towels between the bottom of their cell doors and the floor to keep mice out of their cells, the Milwaukee Journal Sentinel reported Tuesday.

The mice have been a problem for years, Cottingham said. Prisoners’ families have reached out to the state Department of Corrections for help, he said.

Department spokesperson Kevin Hoffman said the prison has brought in a pest control company and the number of complaints has decreased. The company continues to make regular visits to the facility, he said. He added that prisoners need to stop feeding the mice.

“They said they’ve taken certain measures, they put out some mouse traps,” Cottingham told the Milwaukee Journal Sentinel. “Putting up mousetraps is not going to solve this problem at all.”

The maximum security prison, located in Allouez, a Green Bay suburb, has been operating since the 1890s. The Journal Sentinel reports that the prison currently holds 199 more prisoners than it is designed to.

The mice infestation came to light after a bipartisan group of lawmakers asked the state government to shut down the outdated facility, but the effort was not supported. The prison was the scene of a homicide last year and assaults on staff have been reported.