Kimi Raikkonen says he has "always" made his own tweaks to his seat.
The Finn caused a stir on social media when it emerged that he got hands-on in the Alfa Romeo garage to make amendments with files and power-tools to his carbon seat.
"That's normal with me. I've been doing that for years," Raikkonen told motorsport-magazin.com.
"When you get a new seat, it always feels good at first but after hundreds of laps you always find something that pushes your ribs or something.
"I think it's easier if I do it myself because I know exactly where it is not quite right," he added.
Some are saying Alfa Romeo - formerly Sauber - will push to be 'best of the rest' behind the top three teams in 2019.
But Raikkonen said the midfield is actually a "mystery".
"It is still very unclear where we stand," he said. "We do not know 100 per cent where we are, but it's the way it is for everyone.
"We will do our best and then see where we end up in the first race."
