Packed Structs in (gcc)go

I have some old C code that makes somewhat heavy use of packed structures. I'm looking into using Go as a wrapper for this code, but am having difficulty finding a way to pass or even write definitions for these structures.

Example:

import "unsafe";

type AlignTest struct {
    c byte;
    y int16;
    z int16;
    q int32;
}

func main() {

    vr := new(AlignTest);

    fmt.Println(unsafe.Sizeof(*vr),  "\n");

}

Returns 12 rather than the 1+2+2+4 = 9 that I would want with a packed/unaligned struct.

I know that I could just create a byte array and do the parsing manually, but that seems very brittle and error prone...