While his teammate Romain Grosjean has had more of a struggle, the American team are openly happy with Dane Magnussen.
Ekstra Bladet newspaper says that Haas's 2019 option on Magnussen expires at the end of September, but confirmation of the deal could be announced in Singapore or shortly afterwards.
"It was a challenge with a team in the second year when he came," said team boss Gunther Steiner. "It was an opportunity as well, and he took the opportunity."
Haas are fifth in the team rankings heading into this weekend's Singapore Grand Prix.