diff -up mtr-0.84/dns.c.mixed mtr-0.84/dns.c

--- mtr-0.84/dns.c.mixed	2013-06-06 18:56:19.360247890 +0200

+++ mtr-0.84/dns.c	2013-06-06 18:58:09.804233105 +0200

@@ -938,6 +938,8 @@ void dorequest(char *s,int type,word id)

   hp->id = id;	/* htons() deliberately left out (redundant) */

 #ifdef ENABLE_IPV6

   for (i = 0;i < NSCOUNT6;i++) {

+    if (!NSSOCKADDR6(i))

+      continue;

     if (NSSOCKADDR6(i)->sin6_family == AF_INET6)

       (void)sendto(resfd6,buf,r,0,(struct sockaddr *) NSSOCKADDR6(i),

 		   sizeof(struct sockaddr_in6));

@@ -1336,6 +1338,8 @@ void dns_ack6(void)

     if ( addrcmp( (void *) &(from6->sin6_addr), (void *) &localhost6,

                   (int) AF_INET6 ) == 0 ) {

       for (i = 0;i < NSCOUNT6;i++) {

+        if (!NSSOCKADDR6(i))

+          continue;

 	if ( addrcmp( (void *) &(NSSOCKADDR6(i)->sin6_addr),

 		      (void *) &(from6->sin6_addr), (int) AF_INET6 ) == 0 ||

 	     addrcmp( (void *) &(NSSOCKADDR6(i)->sin6_addr),

@@ -1344,6 +1348,8 @@ void dns_ack6(void)

       }

     } else

       for (i = 0;i < NSCOUNT6;i++) {

+        if (!NSSOCKADDR6(i))

+          continue;

 	if ( addrcmp( (void *) &(NSSOCKADDR6(i)->sin6_addr),

 		      (void *) &(from6->sin6_addr), AF_INET6 ) == 0 )

 	  break;