diff --git a/cf/krb-ipv6.m4 b/cf/krb-ipv6.m4
index 20284a4e0..2b4939bd3 100644
--- a/cf/krb-ipv6.m4
+++ b/cf/krb-ipv6.m4
@@ -1,11 +1,44 @@
 dnl $Id$
 dnl
+dnl test for IPv6
+dnl
 AC_DEFUN(AC_KRB_IPV6, [
-AC_MSG_CHECKING(for IPv6)
-foo=no
-AC_EGREP_HEADER(sockaddr_in6, netinet/in.h,
-AC_DEFINE(HAVE_STRUCT_SOCKADDR_IN6) foo=yes)
-AC_EGREP_HEADER(sockaddr_in6, netinet/in6.h,
-AC_DEFINE(HAVE_STRUCT_SOCKADDR_IN6) foo=yes)
-AC_MSG_RESULT($foo)
+AC_CACHE_CHECK(for IPv6,ac_cv_lib_ipv6,
+AC_TRY_COMPILE([
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+#ifdef HAVE_NETINET_IN_H
+#include <netinet/in.h>
+#endif
+#ifdef HAVE_NETINET_IN6_H
+#include <netinet/in6.h>
+#endif
+],
+[
+#if defined(IN6ADDR_ANY_INIT)
+struct in6_addr any = IN6ADDR_ANY_INIT;
+#elif defined(IPV6ADDR_ANY_INIT)
+struct in6_addr any = IPV6ADDR_ANY_INIT;
+#else
+#error no any?
+#endif
+ struct sockaddr_in6 sin6;
+ int s;
+
+ s = socket(AF_INET6, SOCK_DGRAM, 0);
+
+ sin6.sin6_family = AF_INET6;
+ sin6.sin6_port = htons(17);
+ sin6.sin6_addr = any;
+ bind(s, (struct sockaddr *)&sin6, sizeof(sin6));
+],
+ac_cv_lib_ipv6=yes,
+ac_cv_lib_ipv6=no))
+if test "$ac_cv_lib_ipv6" = yes; then
+  AC_DEFINE(HAVE_STRUCT_SOCKADDR_IN6)
+fi
 ])