diff --git a/src/core/netif.c b/src/core/netif.c
index 37e7374a..9e9400da 100644
--- a/src/core/netif.c
+++ b/src/core/netif.c
@@ -897,7 +897,7 @@ netif_poll_all(void)
  *         -1: address not found on this netif
  */
 s8_t
-netif_get_ip6_addr_match(struct netif *netif, ip6_addr_t *ip6addr)
+netif_get_ip6_addr_match(struct netif *netif, const ip6_addr_t *ip6addr)
 {
   s8_t i;
   for (i = 0; i < LWIP_IPV6_NUM_ADDRESSES; i++) {
@@ -968,7 +968,7 @@ netif_create_ip6_linklocal_address(struct netif *netif, u8_t from_mac_48bit)
  * @param chosen_idx if != NULL, the chosen IPv6 address index will be stored here
  */
 err_t
-netif_add_ip6_address(struct netif *netif, ip6_addr_t *ip6addr, s8_t *chosen_idx)
+netif_add_ip6_address(struct netif *netif, const ip6_addr_t *ip6addr, s8_t *chosen_idx)
 {
   s8_t i;
 
diff --git a/src/include/lwip/netif.h b/src/include/lwip/netif.h
index 3c63223f..837645b9 100644
--- a/src/include/lwip/netif.h
+++ b/src/include/lwip/netif.h
@@ -400,9 +400,9 @@ void netif_poll_all(void);
 #define netif_ip6_addr_set(netif, i, addr6) do { ip6_addr_set(ip_2_ip6(&((netif)->ip6_addr[i])), addr6); IP_SET_TYPE_VAL((netif)->ip6_addr[i], IPADDR_TYPE_V6); } while(0)
 #define netif_ip6_addr_state(netif, i)  ((netif)->ip6_addr_state[i])
 #define netif_ip6_addr_set_state(netif, i, state)  ((netif)->ip6_addr_state[i] = (state))
-s8_t netif_get_ip6_addr_match(struct netif *netif, ip6_addr_t *ip6addr);
+s8_t netif_get_ip6_addr_match(struct netif *netif, const ip6_addr_t *ip6addr);
 void netif_create_ip6_linklocal_address(struct netif *netif, u8_t from_mac_48bit);
-err_t netif_add_ip6_address(struct netif *netif, ip6_addr_t *ip6addr, s8_t *chosen_idx);
+err_t netif_add_ip6_address(struct netif *netif, const ip6_addr_t *ip6addr, s8_t *chosen_idx);
 #endif /* LWIP_IPV6 */
 
 #if LWIP_NETIF_HWADDRHINT