Entity Framework Core migration from a console app not working

I am writing a simple console application to test some EF Core code.

I added the entityframework.commands package.

install-package entityframework.commands -pre

The connection string is correct and tested, but when I execute

Update-Database 

from the package manager I get the following error.

No DbContext was found. Ensure that you're using the correct assembly and that the type is neither abstract nor generic.

Of course, I have a context, just one in the project.