McLaren have confirmed claims that they intend to field an unchanged driver lineup for 2018.
"I think McLaren is trying to keep the current lineup", he said, referring also to Fernando Alonso, who is yet to agree a new contract beyond 2017.
Belgian Vandoorne entered Formula 1 this year with a brilliant junior career behind him, but the 25-year-old notably struggled alongside Alonso in the first half of the season.
However, he has taken steps forward in the most recent races.
"The biggest problem was that we had so many technical problems that I hardly drove. It took me some time to understand what I had to do with this car to drive it really fast," Vandoorne said.
"Now I feel more comfortable so I'm closer to Fernando in pace, and I need to continue like that."
Indeed, while earlier there was some criticism from within McLaren management, the Honda-powered team's chiefs are now apparently happier with Vandoorne.
"Yes, we are happy with Stoffel," confirmed executive Zak Brown.
"He is in a difficult situation next to Fernando and with the reliability problems we've had, but we think Stoffel is a future world champion. We want to go with the same drivers next year."
McLaren are currently second from bottom in the team standings, six points ahead of Sauber.