By the way, did a little homework on "In the Mouth of Madness" and turns out to not be a Lovecraft adaptation. The title is similar to H.P.'s "At the Mountains of Madness" but the story and the film are not at all related. However, Carpenter seems to be deliberately paying homage to Lovecraft in this manner and in many elements of the film. Lovecraft? No. Lovecraft inspired? Yes!

Tip of the hat to Psycho.