diff --git a/sys/net/gnrc/network_layer/ndp/gnrc_ndp.c b/sys/net/gnrc/network_layer/ndp/gnrc_ndp.c
index 7554f2ff9a..ec9e18b3a7 100644
--- a/sys/net/gnrc/network_layer/ndp/gnrc_ndp.c
+++ b/sys/net/gnrc/network_layer/ndp/gnrc_ndp.c
@@ -373,7 +373,7 @@ void gnrc_ndp_nbr_adv_send(const ipv6_addr_t *tgt, gnrc_netif_t *netif,
             memcpy(&real_dst, dst, sizeof(real_dst));
             adv_flags |= NDP_NBR_ADV_FLAGS_S;
         }
-        /* add SL2AO based on target address */
+        /* add TL2AO based on target address */
         if (supply_tl2a) {
             uint8_t l2tgt[8];
             size_t l2tgt_len;
@@ -389,15 +389,21 @@ void gnrc_ndp_nbr_adv_send(const ipv6_addr_t *tgt, gnrc_netif_t *netif,
                     break;
                 }
                 pkt = hdr;
+                /* Set the Override flag,
+                if the target address is not an anycast address, and
+                we do not provide a proxy service for the target (TODO), and
+                the Target Link Layer Address Option is included. */
+                if (!(netif->ipv6.addrs_flags[tgt_idx] &
+                    GNRC_NETIF_IPV6_ADDRS_FLAGS_ANYCAST)) {
+                    /* If the receipt of an NA has an existing cache entry
+                    which is not in the INCOMPLETE state, and the supplied TLLAO
+                    indicates a different L2 address than the cached address,
+                    then the O-flag takes precedence and the cache entry should be
+                    updated. (Cf. https://tools.ietf.org/html/rfc4861#section-7.2.5) */
+                    adv_flags |= NDP_NBR_ADV_FLAGS_O;
+                }
             }
         }
-        /* TODO: also check if the node provides proxy services for tgt */
-        if ((pkt != NULL) &&
-            (netif->ipv6.addrs_flags[tgt_idx] &
-             GNRC_NETIF_IPV6_ADDRS_FLAGS_ANYCAST)) {
-            /* TL2A is not supplied and tgt is not anycast */
-            adv_flags |= NDP_NBR_ADV_FLAGS_O;
-        }
         /* add neighbor advertisement header */
         hdr = gnrc_ndp_nbr_adv_build(tgt, adv_flags, pkt);
         if (hdr == NULL) {