Putting exact text in a define

[Town, Brad]

I've searched Google and the mailing list for help on this to no avail.
Perhaps someone can help me.  (I'm using Autoconf 2.13 with Cygwin.)

How can I add a define to a Makefile such as this:

... -DCONFIG_DIR=$(sysconfdir)

The thing I thought would work in configure.in:
AC_DEFINE(CONFIG_DIR, "$(sysconfdir)")

What it produced in the Makefile:
-DCONFIG_DIR=\"\$$\(sysconfdir\)\"

What am I doing wrong?

Brad Town