Bus error accessing char [] by index - OS X

[Cam MacRae]

Executing the following example program compiled with

> gdc stringtest.d -o stringtest

I get a bus error on OS X accessing the char array by index (shown in the comments below). 

I imagine this might be a gdc on OS X issue - any other ideas?

import std.stdio;

void main() {
  char[] firstname
  firstname = "Cam";
  char [] a = firstname, b = firstname;
  a[0] = 'H'; //Bus error here
  writefln(b);
}

cheers,
Cam.