The England international began his professional career with Manchester United, although he never made a single senior appearance for them in a competitive game, despite having enjoyed success with his current club West Bromwich Albion.
With Lukasz Fabianski reaching the end of his career, West Ham could do well to bring in a long-term replacement, with Johnstone appearing like a strong possibility given his form in the Championship.
According to the Sun, the Hammers appear to be in advanced talks over a transfer for Johnstone, with the 28-year-old possibly one of many targets the club will aim to sign this summer.
At the end of the season, Johnstone will become a free agent, and he is free to begin discussions with potential English clubs immediately.
If West Ham are to maintain their upward trajectory under David Moyes, they would likely need to acquire four or five new players this summer.
Saviour Paul 1 y
Good