Iterating over an enum associative array

[Nebster]

Hey,

I'm having some problems iterating over an enumerated associative array.
It comes up with this error at compile time:
> Internal error: e2ir.c 4835
I cut the code down to this:
> import std.stdio;
>
> enum int[string] assoc = [";": 0, "=": 1, "+": 2, "-": 2, "*": 3, 
"/": 3];
>
> void main()
> {
>    foreach(op; assoc.byKey())
>            writefln("op: %s", op);
> }

What does this mean/how can I get this to work?

Thanks,
Nebster