diff --git a/src/NetworkManagerUtils.c b/src/NetworkManagerUtils.c
index f7f2b986f8..956a6062d6 100644
--- a/src/NetworkManagerUtils.c
+++ b/src/NetworkManagerUtils.c
@@ -75,6 +75,50 @@ nm_ethernet_address_is_valid (const struct ether_addr *test_addr)
 }
 
 
+/* nm_utils_ip4_address_clear_host_address:
+ * @addr: source ip6 address
+ * @plen: prefix length of network
+ *
+ * returns: the input address, with the host address set to 0.
+ */
+in_addr_t
+nm_utils_ip4_address_clear_host_address (in_addr_t addr, guint8 plen)
+{
+	return addr & nm_utils_ip4_prefix_to_netmask (plen);
+}
+
+	/* nm_utils_ip6_address_clear_host_address:
+ * @dst: destination output buffer, will contain the network part of the @src address
+ * @src: source ip6 address
+ * @plen: prefix length of network
+ *
+ * Note: this function is self assignment save, to update @src inplace, set both
+ * @dst and @src to the same destination.
+ */
+void
+nm_utils_ip6_address_clear_host_address (struct in6_addr *dst, const struct in6_addr *src, guint8 plen)
+{
+	g_return_if_fail (plen <= 128);
+	g_return_if_fail (src);
+	g_return_if_fail (dst);
+
+	if (plen < 128) {
+		guint nbytes = plen / 8;
+		guint nbits = plen % 8;
+
+		if (nbytes && dst != src)
+			memcpy (dst, src, nbytes);
+		if (nbits) {
+			dst->s6_addr[nbytes] = (src->s6_addr[nbytes] & (0xFF << (8 - nbits)));
+			nbytes++;
+		}
+		if (nbytes <= 15)
+			memset (&dst->s6_addr[nbytes], 0, 16 - nbytes);
+	} else if (src != dst)
+		*dst = *src;
+}
+
+
 int
 nm_spawn_process (const char *args)
 {
diff --git a/src/NetworkManagerUtils.h b/src/NetworkManagerUtils.h
index d33ceda507..ee234dda80 100644
--- a/src/NetworkManagerUtils.h
+++ b/src/NetworkManagerUtils.h
@@ -35,6 +35,9 @@
 
 gboolean nm_ethernet_address_is_valid (const struct ether_addr *test_addr);
 
+in_addr_t nm_utils_ip4_address_clear_host_address (in_addr_t addr, guint8 plen);
+void nm_utils_ip6_address_clear_host_address (struct in6_addr *dst, const struct in6_addr *src, guint8 plen);
+
 int nm_spawn_process (const char *args);
 
 gboolean nm_match_spec_string (const GSList *specs, const char *string);
diff --git a/src/rdisc/nm-lndp-rdisc.c b/src/rdisc/nm-lndp-rdisc.c
index 5fb28778fc..3b0b0365b4 100644
--- a/src/rdisc/nm-lndp-rdisc.c
+++ b/src/rdisc/nm-lndp-rdisc.c
@@ -428,29 +428,6 @@ fill_address_from_mac (struct in6_addr *address, const char *mac)
 	memcpy (identifier + 5, mac + 3, 3);
 }
 
-/* Ensure the given address is masked with its prefix and that all host
- * bits are set to zero.  Some IPv6 router advertisement daemons (eg, radvd)
- * don't enforce this in their configuration.
- */
-static void
-set_address_masked (struct in6_addr *dst, struct in6_addr *src, guint8 plen)
-{
-	guint nbytes = plen / 8;
-	guint nbits = plen % 8;
-
-	g_return_if_fail (plen <= 128);
-	g_assert (src);
-	g_assert (dst);
-
-	if (plen >= 128)
-		*dst = *src;
-	else {
-		memset (dst, 0, sizeof (*dst));
-		memcpy (dst, src, nbytes);
-		dst->s6_addr[nbytes] = (src->s6_addr[nbytes] & (0xFF << (8 - nbits)));
-	}
-}
-
 static int
 receive_ra (struct ndp *ndp, struct ndp_msg *msg, gpointer user_data)
 {
@@ -529,7 +506,7 @@ receive_ra (struct ndp *ndp, struct ndp_msg *msg, gpointer user_data)
 		/* Device route */
 		memset (&route, 0, sizeof (route));
 		route.plen = ndp_msg_opt_prefix_len (msg, offset);
-		set_address_masked (&route.network, ndp_msg_opt_prefix (msg, offset), route.plen);
+		nm_utils_ip6_address_clear_host_address (&route.network, ndp_msg_opt_prefix (msg, offset), route.plen);
 		route.timestamp = now;
 		if (ndp_msg_opt_prefix_flag_on_link (msg, offset)) {
 			route.lifetime = ndp_msg_opt_prefix_valid_time (msg, offset);
@@ -560,7 +537,7 @@ receive_ra (struct ndp *ndp, struct ndp_msg *msg, gpointer user_data)
 		memset (&route, 0, sizeof (route));
 		route.gateway = gateway.address;
 		route.plen = ndp_msg_opt_route_prefix_len (msg, offset);
-		set_address_masked (&route.network, ndp_msg_opt_route_prefix (msg, offset), route.plen);
+		nm_utils_ip6_address_clear_host_address (&route.network, ndp_msg_opt_route_prefix (msg, offset), route.plen);
 		route.timestamp = now;
 		route.lifetime = ndp_msg_opt_route_lifetime (msg, offset);
 		route.preference = translate_preference (ndp_msg_opt_route_preference (msg, offset));
diff --git a/src/tests/test-general.c b/src/tests/test-general.c
index 649653c75e..3fd7115cb0 100644
--- a/src/tests/test-general.c
+++ b/src/tests/test-general.c
@@ -60,6 +60,76 @@ test_nm_utils_ascii_str_to_int64 (void)
 	test_nm_utils_ascii_str_to_int64_do ("\r\n\t10000\t\n\t\n", 10, 0, 10000, -1, 0, 10000);
 }
 
+/* Reference implementation for nm_utils_ip6_address_clear_host_address.
+ * Taken originally from set_address_masked(), src/rdisc/nm-lndp-rdisc.c
+ **/
+static void
+ip6_address_clear_host_address_reference (struct in6_addr *dst, struct in6_addr *src, guint8 plen)
+{
+	guint nbytes = plen / 8;
+	guint nbits = plen % 8;
+
+	g_return_if_fail (plen <= 128);
+	g_assert (src);
+	g_assert (dst);
+
+	if (plen >= 128)
+		*dst = *src;
+	else {
+		memset (dst, 0, sizeof (*dst));
+		memcpy (dst, src, nbytes);
+		dst->s6_addr[nbytes] = (src->s6_addr[nbytes] & (0xFF << (8 - nbits)));
+	}
+}
+
+static void
+_randomize_in6_addr (struct in6_addr *addr, GRand *rand)
+{
+	int i;
+
+	for (i=0; i < 4; i++)
+		((guint32 *)addr)[i] = g_rand_int (rand);
+}
+
+static void
+test_nm_utils_ip6_address_clear_host_address (void)
+{
+	GRand *rand = g_rand_new ();
+	int plen, i;
+
+	g_rand_set_seed (rand, 0);
+
+	for (plen = 0; plen <= 128; plen++) {
+		for (i =0; i<50; i++) {
+			struct in6_addr addr_src, addr_ref;
+			struct in6_addr addr1, addr2;
+
+			_randomize_in6_addr (&addr_src, rand);
+			_randomize_in6_addr (&addr_ref, rand);
+			_randomize_in6_addr (&addr1, rand);
+			_randomize_in6_addr (&addr2, rand);
+
+			addr1 = addr_src;
+			ip6_address_clear_host_address_reference (&addr_ref, &addr1, plen);
+
+			_randomize_in6_addr (&addr1, rand);
+			_randomize_in6_addr (&addr2, rand);
+			addr1 = addr_src;
+			nm_utils_ip6_address_clear_host_address (&addr2, &addr1, plen);
+			g_assert_cmpint (memcmp (&addr1, &addr_src, sizeof (struct in6_addr)), ==, 0);
+			g_assert_cmpint (memcmp (&addr2, &addr_ref, sizeof (struct in6_addr)), ==, 0);
+
+			/* test for self assignment/inplace update. */
+			_randomize_in6_addr (&addr1, rand);
+			addr1 = addr_src;
+			nm_utils_ip6_address_clear_host_address (&addr1, &addr1, plen);
+			g_assert_cmpint (memcmp (&addr1, &addr_ref, sizeof (struct in6_addr)), ==, 0);
+		}
+	}
+
+	g_rand_free (rand);
+}
+
 /*******************************************/
 
 int
@@ -70,6 +140,7 @@ main (int argc, char **argv)
 	g_type_init ();
 
 	g_test_add_func ("/general/nm_utils_ascii_str_to_int64", test_nm_utils_ascii_str_to_int64);
+	g_test_add_func ("/general/nm_utils_ip6_address_clear_host_address", test_nm_utils_ip6_address_clear_host_address);
 
 	return g_test_run ();
 }