Double pointer as parameter doesn't work with typedef

I am trying to pass a pointer by reference to a function and get that function to point my pointer at a structure that it finds.

char get_structure(STRUCTURE **ptr)
{
    if(foundstructure)
    {
        *ptr = &theStructure;
        return 1;
    }
    return 0;
}

This works how I expect it, but when I try and declare the function prototype in the header file:

char get_structure(STRUCTURE **ptr);

I always get a compiler error:

error C141: syntax error near '*', expected ')'

I don't get an error when this is a defined type like char, int or long, but I get the error when this is a pointer to a typedef that I have defined.

How can I declare this in my header file without an error?

Nathan