Elon Musk clapped back at San Francisco’s Department of Building Inspection after it said it was investigating complaints that makeshift bedrooms had been set up at Twitter’s headquarters in the city. “We need to make sure the building is being used as intended,” Patrick Hannan, a spokesman for the department, told the Washington Post. “There are different building code requirements for residential buildings, including those being used for short-term stays. These codes make sure people are using spaces safely.” The complaint came after reports that offices in the building were being made into sleeping spaces following Musk’s vow to establish a “hardcore” working culture at the tech company. In a tweet replying to news of the investigation, Musk asked San Francisco’s Mayor London Breed (D) where her “priorities” are, adding: “So city of SF attacks companies providing beds for tired employees instead of making sure kids are safe from fentanyl.”