diff --git a/src/core/netif.c b/src/core/netif.c
index 718b5587..c2a64d6f 100644
--- a/src/core/netif.c
+++ b/src/core/netif.c
@@ -958,7 +958,7 @@ netif_alloc_client_data_id(void)
 
 #if LWIP_IPV6
 void
-netif_ip6_addr_set(struct netif *netif, s8_t addr_idx, ip6_addr_t *addr6)
+netif_ip6_addr_set(struct netif *netif, s8_t addr_idx, const ip6_addr_t *addr6)
 {
   LWIP_ASSERT("addr6 != NULL", addr6 != NULL);
   netif_ip6_addr_set_parts(netif, addr_idx, addr6->addr[0], addr6->addr[1],
diff --git a/src/include/lwip/netif.h b/src/include/lwip/netif.h
index 782f7b27..6b727044 100644
--- a/src/include/lwip/netif.h
+++ b/src/include/lwip/netif.h
@@ -433,7 +433,7 @@ u8_t netif_alloc_client_data_id(void);
 #define netif_ip_addr6(netif, i)  ((const ip_addr_t*)(&((netif)->ip6_addr[i])))
 /** @ingroup netif */
 #define netif_ip6_addr(netif, i)  ((const ip6_addr_t*)ip_2_ip6(&((netif)->ip6_addr[i])))
-void netif_ip6_addr_set(struct netif *netif, s8_t addr_idx, ip6_addr_t *addr6);
+void netif_ip6_addr_set(struct netif *netif, s8_t addr_idx, const ip6_addr_t *addr6);
 void netif_ip6_addr_set_parts(struct netif *netif, s8_t addr_idx, u32_t i0, u32_t i1, u32_t i2, u32_t i3);
 #define netif_ip6_addr_state(netif, i)  ((netif)->ip6_addr_state[i])
 void netif_ip6_addr_set_state(struct netif* netif, s8_t addr_idx, u8_t state);