Arizona State House Speaker David Gowan has reimbursed the state more than $12,000 for travel expenses. Nearly $10,000 of this was for mileage reimbursements he received for using his personal vehicle, when in fact he was using a state vehicle, as well as mileage overestimates, the Arizona Republic reported.

A spokeswoman for Arizona House Republicans attributed this to a mistake made by Gowan’s assistant.