diff -r d014b78896f9 autoconf/m4/unreal.m4
--- a/autoconf/m4/unreal.m4	Sat Jul 17 07:19:48 2010 -0400
+++ b/autoconf/m4/unreal.m4	Sun Jul 18 14:32:34 2010 -0400
@@ -125,7 +125,8 @@
 		dnl Make sure that linking against cURL works rather than letting the user
 		dnl find out after compiling most of his program. ~ohnobinki
 		IRCDLIBS="$IRCDLIBS $CURLLIBS"
-		CFLAGS="$CFLAGS $CURLCFLAG -DUSE_LIBCURL"
+		CFLAGS="$CFLAGS $CURLCFLAG"
+		AC_DEFINE([USE_LIBCURL], [], [Define if you have libcurl installed to get remote includes and MOTD support])
 
 		AC_MSG_CHECKING([curl_easy_init() in $CURLLIBS])
 		LIBS_SAVEDA="$LIBS"
@@ -218,11 +219,10 @@
 		if test -f "$dir/include/zlib.h"; then
 			AC_MSG_RESULT(found in $zlibdir)
 			found_zlib="yes";
-			if test "$zlibdir" = "/usr" ; then
-				CFLAGS="$CFLAGS -DZIP_LINKS";
-			else
-				CFLAGS="$CFLAGS -I$zlibdir/include -DZIP_LINKS";
+			if test "$zlibdir" != "/usr" ; then
+				CFLAGS="$CFLAGS -I$zlibdir/include";
 			fi
+			AC_DEFINE([ZIP_LINKS], [], [Define if you have zlib and want zip links support.])
 		break
 		fi
 	done
diff -r d014b78896f9 configure.ac
--- a/configure.ac	Sat Jul 17 07:19:48 2010 -0400
+++ b/configure.ac	Sun Jul 18 14:32:34 2010 -0400
@@ -516,19 +516,17 @@
 exit(0);
 }
 ], AC_MSG_RESULT([yes]), [
+# must be passed on the commandline to avoid a ``warning, you redefined something''
 FD_SETSIZE="-DFD_SETSIZE=$ac_fd"
 AC_MSG_RESULT(no)
 ])
 AC_SUBST([FD_SETSIZE])
+
 case `uname -s` in
-*SunOS*)
-CFLAGS="$CFLAGS -D_SOLARIS"
-IRCDLIBS="$IRCDLIBS -lresolv "
-;;
-*solaris*)
-CFLAGS="$CFLAGS -D_SOLARIS"
-IRCDLIBS="$IRCDLIBS -lresolv "
-;;
+	*SunOS*|*solaris*)
+		AC_DEFINE([_SOLARIS], [], [Define if you are compiling unrealircd on Sun's (or Oracle's?) Solaris])
+		IRCDLIBS="$IRCDLIBS -lresolv "
+		;;
 esac
 
 dnl c-ares needs PATH_SEPARATOR set or it will
@@ -640,3 +638,10 @@
 AC_OUTPUT(Makefile src/modules/Makefile unreal ircdcron/ircdchk)
 chmod 0700 unreal
 chmod 0700 ircdcron/ircdchk
+
+# this does not catch the case where one once passed --with-fd-setsize
+# and then later doesn't pass it (or passes
+# --without-fd-setsize). Catching those cases would be unclean and not
+# even that helpful.
+AS_IF([test -n "$FD_SETSIZE"],
+	[AC_MSG_WARN([You must recompile unrealircd by running \`make clean' and then \`make' or \`make install' if you changed your --with-fd-setsize setting!])])