[Dev-C++] Problem with RegisterWindowMessage()

I have a little problem. I have a header file which I include in my main
file (surprise surprise). In the header I have the following:

const UINT WM_MYMESSAGE = RegisterWindowMessage(_T("some message"));

Right, now in my main WindowProc I have a switch statement like so:

LRESULT CALLBACK WindowProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM
lParam)
{
    switch (message)                  /* handle the messages */
    {
      case WM_DESTROY:
            PostQuitMessage (0);       /* send a WM_QUIT to the message
queue */
            break;
	/* 
		And some more message handlers here
		more
		more
	*/
	case WM_MYMESSAGE:
		/*Do some stuff*/
	default:
		return DefWindowProc (hwnd, message, wParam, lParam);
    }
    return 0;
}

So far so good. Now when I compile I get the following little message:

"case label `WM_MYMESSAGE' does not reduce to an integer constant"

Now, personally, I thought that a "const UINT" was an integer constant, but
clearly g++ disagrees. The funny thing is I have used similar code with VC++
v6 and not had the same problem. Any ideas of how I can convince g++ that
this is the case would be appreciated.

_____________________________
Marc Heiligers

PS. I've had coffee before I wrote this, so I'm pretty sure I'm thinking
straight (for a change).