Is this joist ok?

Was fixing a floorboard that the previous owner had cut too short(didn't go between 2 joists) and noticed this cut out in the joists presumably when the radiators were added. Is this anything I need to worry about or will it be strong enough?

Was fixing a floorboard that the previous owner had cut too short(didn't go between 2 joists) and noticed this cut out in the joists presumably when the radiators were added. Is this anything I need to worry about or will it be strong enough?