A link would have been helpful.
There is a link to
Dark August
at the top of this messageboard (as with any movie on Filmboards). Perhaps you didn't see that. In any case, it's a simple matter to look up a movie on IMDb and Wikipedia.

A link would have been helpful. From the plot description, it does sound like Thinner.
If you can’t say something nice, say something clever but devastating.

This message has been deleted.

Seems rather obscure…released 7 or 8 years before the Thinner novel, and 2 decades before the film version. Maybe you've stumbled onto plagiarism.

I was hoping somebody might have done that already, but I can't find any comparisons online.

Why not watch it and come back with compare and contrast essay

Both movies have IMDb pages, obviously. The plot outline of
Dark August
is as follows: "A man accidentally runs down a young girl and has a curse placed on him by the girl's father, an occultist. He goes to a spiritualist for help in fighting the curse." This sounds very much like
Thinner
, except that in
Thinner
the main character goes to a mobster for help.

You might consider posting a link so we can evaluate and comment.
If you can’t say something nice, say something clever but devastating.