Seattle is a metropolitan city on the water. Thus, we have rats. And unless the Pied Piper marches them into the sound or, more realistically, Amazon develops a way to convert their body heat into energy Matrix-style, rodents will forever remain part of the urban landscape.

While the rodent problem isn’t new, another troubling population has increased in recent years: vacant buildings—a particularly pest-friendly side effect of growing urban redevelopment. That’s right, homelessness is on the rise and rent continues to skyrocket throughout the city, but the rat population has a plethora of nice, comfortable housing in the form of abandoned buildings waiting to be redeveloped. And what’s worse, says Darcy Webber of King County Public Health, is that once these decrepit lots are leveled, the resident rat families disperse into other neighborhoods and do what rats do: “breed prolifically.”

Rodent mating habits we can’t change. But the vacant building problem we can—hopefully. Starting January 1, in accordance with a new code passed by the city council, builders looking to redevelop an existing property must first hire a pest control company to remove any rats in and around the building or confirm there are no furry squatters.

“This is not some rogue standard,” says Bryan Stevens of the Seattle Department of Construction and Inspections, which partnered with King County Health to enact the code. Cities like Shoreline and Kirkland already have similar programs in place.

Vacant buildings aren’t the only contributing factor to rodents in our city—increased density brought on by the currently booming human population is another—but this year’s code revision opened the door to at least combat that specific problem. “There is no one easy way to address the rodent population,” says Webber. “But there are many, many ways to help.” She hopes this new standard will reduce the 60 rat-related vacant building complaints the county gets in an average year. Developers haven’t put up much of a fight against the law, so as long as the market stays red hot, Seattle’s rats will have to pine for affordable housing just like the rest of us.