diff --git a/configure.ac b/configure.ac
index 29eec20..e523842 100644
--- a/configure.ac
+++ b/configure.ac
@@ -33,25 +33,40 @@ AC_SUBST(DEBUG_OPTS)
 AC_ARG_ENABLE(ipv6, 
 	      AS_HELP_STRING([--disable-ipv6], 
               		     [disable ipv6 support (default is autodetect)]), 
-	      		     ac_cv_have_ipv6=$enable_ipv6,)
+	      		     uvrrpd_want_ipv6=$enable_ipv6,)
 
 dnl check for ipv6 
-if test "$ac_cv_have_ipv6" != no; then
+if test x"uvrrpd_want_ipv6" != xno; then
 	AC_CHECK_TYPES(struct in6_addr,,,[#include <netinet/in.h>])
 	AC_CHECK_TYPES(struct ip6_hdr,,,[#include <netinet/ip6.h>])
 	AC_CHECK_DECLS(AF_INET6,,,[#include <sys/socket.h>])
 	AC_MSG_CHECKING(for IPv6 headers and structures)
-	ac_cv_have_ipv6=no
+	uvrrpd_want_ipv6=no
 
-	if test "$ac_cv_type_struct_in6_addr" = yes; then
-		if test "$ac_cv_type_struct_ip6_hdr" = yes; then
-			if test "$ac_cv_have_decl_AF_INET6" = yes; then
-				ac_cv_have_ipv6=yes
-				AC_DEFINE([HAVE_IP6], 1, [Define to enable IPv6 support])
+	if test x"$ac_cv_type_struct_in6_addr" = xyes; then
+		if test x"$ac_cv_type_struct_ip6_hdr" = xyes; then
+			if test x"$ac_cv_have_decl_AF_INET6" = xyes; then
+				uvrrpd_want_ipv6=yes
 			fi
 		fi
 	fi
-	AC_MSG_RESULT($ac_cv_have_ipv6)
+	AC_MSG_RESULT($uvrrpd_want_ipv6)
+fi
+
+dnl check for ipv6 multicast (required)
+if test x"uvrrpd_want_ipv6" != xno; then
+	AC_CHECK_DECLS(IPV6_ADD_MEMBERSHIP,,,[#include <netinet/in.h>])
+	AC_CHECK_TYPES(struct ipv6_mreq,,,[#include <netinet/in.h>])
+	AC_MSG_CHECKING(for IPv6 multicast support)
+	uvrrpd_want_ipv6_mcast=no
+
+	if test x"$ac_cv_have_decl_IPV6_ADD_MEMBERSHIP" = xyes; then
+		if test x"$ac_cv_type_struct_ipv6_mreq" = xyes; then
+			uvrrpd_want_ipv6_mcast=yes
+			AC_DEFINE([HAVE_IP6], 1, [Define to enable IPv6 support])
+		fi
+	fi
+	AC_MSG_RESULT($uvrrpd_want_ipv6_mcast)
 fi