Police are investigating a second deliberate fire in Desborough in two days, but say the two are not linked.
The most recent took place in Stoke Road at about 9pm yesterday (Monday).
A small outbuilding was set alight deliberately.
No arrests have been made and police are appealing for witnesses to call them on 101.
The force says this fire is not linked to a significant deliberate blaze in Stoke Albany Road at 9.50pm on Sunday.
Three men who were arrested over that fire have been released under police investigation.