--- lib/autoconf/c.m4~	2006-11-08 09:26:44.000000000 +0100
+++ lib/autoconf/c.m4	2009-09-16 21:10:08.000000000 +0200
@@ -179,7 +179,7 @@ m4_define([AC_LANG_PROGRAM(C)],
 m4_ifdef([_AC_LANG_PROGRAM_C_F77_HOOKS], [_AC_LANG_PROGRAM_C_F77_HOOKS])[]dnl
 m4_ifdef([_AC_LANG_PROGRAM_C_FC_HOOKS], [_AC_LANG_PROGRAM_C_FC_HOOKS])[]dnl
 int
-main ()
+main (void)
 {
 dnl Do *not* indent the following line: there may be CPP directives.
 dnl Don't move the `;' right after for the same reason.