diff --git a/test/test-udp-multicast-join.c b/test/test-udp-multicast-join.c
index 053d2f79..6399d9c9 100644
--- a/test/test-udp-multicast-join.c
+++ b/test/test-udp-multicast-join.c
@@ -101,7 +101,7 @@ TEST_IMPL(udp_multicast_join) {
   uv_buf_t buf;
   struct sockaddr_in addr;
 
-  ASSERT(0 == uv_ip4_addr("127.0.0.1", TEST_PORT, &addr));
+  ASSERT(0 == uv_ip4_addr("0.0.0.0", TEST_PORT, &addr));
 
   r = uv_udp_init(uv_default_loop(), &server);
   ASSERT(r == 0);
@@ -124,6 +124,8 @@ TEST_IMPL(udp_multicast_join) {
 
   buf = uv_buf_init("PING", 4);
 
+  ASSERT(0 == uv_ip4_addr("239.255.0.1", TEST_PORT, &addr));
+
   /* server sends "PING" */
   r = uv_udp_send(&req,
                   &server,
diff --git a/test/test-udp-multicast-join6.c b/test/test-udp-multicast-join6.c
index bda5e20e..49d253ab 100644
--- a/test/test-udp-multicast-join6.c
+++ b/test/test-udp-multicast-join6.c
@@ -30,6 +30,19 @@
 #define CHECK_HANDLE(handle) \
   ASSERT((uv_udp_t*)(handle) == &server || (uv_udp_t*)(handle) == &client)
 
+#if defined(__APPLE__)          || \
+    defined(_AIX)               || \
+    defined(__MVS__)            || \
+    defined(__FreeBSD_kernel__) || \
+    defined(__NetBSD__)         || \
+    defined(__OpenBSD__)
+  #define MULTICAST_ADDR "ff02::1%lo0"
+  #define INTERFACE_ADDR "::1%lo0"
+#else
+  #define MULTICAST_ADDR "ff02::1"
+  #define INTERFACE_ADDR NULL
+#endif
+
 static uv_udp_t server;
 static uv_udp_t client;
 
@@ -96,16 +109,35 @@ static void cl_recv_cb(uv_udp_t* handle,
 }
 
 
+static int can_ipv6_external(void) {
+  uv_interface_address_t* addr;
+  int supported;
+  int count;
+  int i;
+
+  if (uv_interface_addresses(&addr, &count))
+    return 0;  /* Assume no IPv6 support on failure. */
+
+  supported = 0;
+  for (i = 0; supported == 0 && i < count; i += 1)
+    supported = (AF_INET6 == addr[i].address.address6.sin6_family &&
+                 !addr[i].is_internal);
+
+  uv_free_interface_addresses(addr, count);
+  return supported;
+}
+
+
 TEST_IMPL(udp_multicast_join6) {
   int r;
   uv_udp_send_t req;
   uv_buf_t buf;
   struct sockaddr_in6 addr;
 
-  if (!can_ipv6())
-    RETURN_SKIP("IPv6 not supported");
+  if (!can_ipv6_external())
+    RETURN_SKIP("No external IPv6 interface available");
 
-  ASSERT(0 == uv_ip6_addr("::1", TEST_PORT, &addr));
+  ASSERT(0 == uv_ip6_addr("::", TEST_PORT, &addr));
 
   r = uv_udp_init(uv_default_loop(), &server);
   ASSERT(r == 0);
@@ -117,17 +149,7 @@ TEST_IMPL(udp_multicast_join6) {
   r = uv_udp_bind(&client, (const struct sockaddr*) &addr, 0);
   ASSERT(r == 0);
 
-  /* join the multicast channel */
-#if defined(__APPLE__)          || \
-    defined(_AIX)               || \
-    defined(__MVS__)            || \
-    defined(__FreeBSD_kernel__) || \
-    defined(__NetBSD__)         || \
-    defined(__OpenBSD__)
-  r = uv_udp_set_membership(&client, "ff02::1", "::1%lo0", UV_JOIN_GROUP);
-#else
-  r = uv_udp_set_membership(&client, "ff02::1", NULL, UV_JOIN_GROUP);
-#endif
+  r = uv_udp_set_membership(&client, MULTICAST_ADDR, INTERFACE_ADDR, UV_JOIN_GROUP);
   if (r == UV_ENODEV) {
     MAKE_VALGRIND_HAPPY();
     RETURN_SKIP("No ipv6 multicast route");
@@ -140,6 +162,8 @@ TEST_IMPL(udp_multicast_join6) {
 
   buf = uv_buf_init("PING", 4);
 
+  ASSERT(0 == uv_ip6_addr(MULTICAST_ADDR, TEST_PORT, &addr));
+
   /* server sends "PING" */
   r = uv_udp_send(&req,
                   &server,