diff --git a/os/net/ipv6/uip-ds6-nbr.c b/os/net/ipv6/uip-ds6-nbr.c
index c83fa7674..0db8a0f45 100644
--- a/os/net/ipv6/uip-ds6-nbr.c
+++ b/os/net/ipv6/uip-ds6-nbr.c
@@ -149,6 +149,19 @@ uip_ds6_nbr_add(const uip_ipaddr_t *ipaddr, const uip_lladdr_t *lladdr,
     }
   }
 
+  if(list_length(nbr_entry->uip_ds6_nbrs) < UIP_DS6_NBR_MAX_6ADDRS_PER_NBR) {
+    /* it has room to add another IPv6 address */
+  } else {
+    /*
+     * it's already had the maximum number of IPv6 addresses; cannot
+     * add another.
+     */
+    LOG_ERR("%s: no room in nbr_entry for ", __func__);
+    LOG_ERR_LLADDR((const linkaddr_t *)lladdr);
+    LOG_ERR_("\n");
+    return NULL;
+  }
+
   if((nbr = (uip_ds6_nbr_t *)memb_alloc(&uip_ds6_nbr_memb)) == NULL) {
     LOG_ERR("%s: cannot allocate a new uip_ds6_nbr\n", __func__);
     if(list_length(nbr_entry->uip_ds6_nbrs) == 0) {
diff --git a/os/net/ipv6/uip-ds6-nbr.h b/os/net/ipv6/uip-ds6-nbr.h
index 809f01d2b..6479c972e 100644
--- a/os/net/ipv6/uip-ds6-nbr.h
+++ b/os/net/ipv6/uip-ds6-nbr.h
@@ -75,6 +75,14 @@
 #define UIP_DS6_NBR_MULTI_IPV6_ADDRS 0
 #endif /* UIP_DS6_NBR_CONF_MULTI_IPV6_ADDRS */
 
+/** \brief Set the maximum number of IPv6 addresses per link-layer
+ * address */
+#ifdef UIP_DS6_NBR_CONF_MAX_6ADDRS_PER_NBR
+#define UIP_DS6_NBR_MAX_6ADDRS_PER_NBR UIP_DS6_NBR_CONF_MAX_6ADDRS_PER_NBR
+#else
+#define UIP_DS6_NBR_MAX_6ADDRS_PER_NBR 2
+#endif /* UIP_DS6_NBR_CONF_MAX_6ADDRS_PER_NBR */
+
 /** \brief Set the maximum number of neighbor cache entries */
 #ifdef UIP_DS6_NBR_CONF_MAX_NEIGHBOR_CACHES
 #define UIP_DS6_NBR_MAX_NEIGHBOR_CACHES UIP_DS6_NBR_CONF_MAX_NEIGHBOR_CACHES