Pointer to a global variable

Question

So, I had a code like this (detail):

namespace itssafe
{
    public unsafe partial class testing : Form
    {
        unsafe private static int original = 10;
        unsafe private int tmp;

        unsafe setter() // I'll use this several time
        {
            tmp = original;
        }

        unsafe private void Form1_Load(object sender, EventArgs e)
        {
            setter();
        }

        unsafe private void timers_Tick(object sender, EventArgs e)
        {
            int* counter;   // working
            counter = &tmp; // not working, but I need this
        }
    }
}

And I had a global variable, called "tmp" and I need to create a pointer what point to it. But I can't, because I get "CS0212 You can only take the address of an unfixed expression inside of a fixed statement initializer" error. But the variable is global so I can't create in this method, because I need to use elsewhere too. What can I do?

I know I'm using to many unnecessary "unsafe", but i'm so desperate.