diff --git a/src/core/ipv4/icmp.c b/src/core/ipv4/icmp.c
index a9cf3b66..941031ee 100644
--- a/src/core/ipv4/icmp.c
+++ b/src/core/ipv4/icmp.c
@@ -83,7 +83,7 @@ icmp_input(struct pbuf *p, struct netif *inp)
   const struct ip_hdr *iphdr_in;
   struct ip_hdr *iphdr;
   s16_t hlen;
-  ip4_addr_t* src;
+  const ip4_addr_t* src;
 
   ICMP_STATS_INC(icmp.recv);
   MIB2_STATS_INC(mib2.icmpinmsgs);
@@ -110,7 +110,7 @@ icmp_input(struct pbuf *p, struct netif *inp)
     if (ip_addr_ismulticast(ip_current_dest_addr())) {
 #if LWIP_MULTICAST_PING
       /* For multicast, use address of receiving interface as source address */
-      src = &inp->ip_addr;
+      src = netif_ip4_addr(inp);
 #else /* LWIP_MULTICAST_PING */
       LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: Not echoing to multicast pings\n"));
       goto icmperr;
diff --git a/src/core/ipv6/icmp6.c b/src/core/ipv6/icmp6.c
index d2c40f15..ecc4b520 100644
--- a/src/core/ipv6/icmp6.c
+++ b/src/core/ipv6/icmp6.c
@@ -81,7 +81,7 @@ icmp6_input(struct pbuf *p, struct netif *inp)
 {
   struct icmp6_hdr *icmp6hdr;
   struct pbuf * r;
-  ip6_addr_t * reply_src;
+  const ip6_addr_t * reply_src;
 
   ICMP6_STATS_INC(icmp6.recv);
 
@@ -272,7 +272,8 @@ icmp6_send_response(struct pbuf *p, u8_t code, u32_t data, u8_t type)
 {
   struct pbuf *q;
   struct icmp6_hdr *icmp6hdr;
-  ip6_addr_t *reply_src, *reply_dest;
+  const ip6_addr_t *reply_src;
+  ip6_addr_t *reply_dest;
   ip6_addr_t reply_src_local, reply_dest_local;
   struct ip6_hdr *ip6hdr;
   struct netif *netif;
diff --git a/src/core/ipv6/ip6.c b/src/core/ipv6/ip6.c
index eca72cde..61971589 100644
--- a/src/core/ipv6/ip6.c
+++ b/src/core/ipv6/ip6.c
@@ -206,10 +206,10 @@ ip6_route(const ip6_addr_t *src, const ip6_addr_t *dest)
  * @return the most suitable source address to use, or NULL if no suitable
  *         source address is found
  */
-ip6_addr_t *
+const ip6_addr_t *
 ip6_select_source_address(struct netif *netif, const ip6_addr_t * dest)
 {
-  ip6_addr_t * src = NULL;
+  const ip6_addr_t *src = NULL;
   u8_t i;
 
   /* If dest is link-local, choose a link-local source. */
diff --git a/src/include/lwip/ip6.h b/src/include/lwip/ip6.h
index dcb3270a..012302ef 100644
--- a/src/include/lwip/ip6.h
+++ b/src/include/lwip/ip6.h
@@ -162,7 +162,7 @@ PACK_STRUCT_END
 
 
 struct netif *ip6_route(const ip6_addr_t *src, const ip6_addr_t *dest);
-ip6_addr_t   *ip6_select_source_address(struct netif *netif, const ip6_addr_t * dest);
+const ip6_addr_t *ip6_select_source_address(struct netif *netif, const ip6_addr_t * dest);
 err_t         ip6_input(struct pbuf *p, struct netif *inp);
 err_t         ip6_output(struct pbuf *p, const ip6_addr_t *src, const ip6_addr_t *dest,
                          u8_t hl, u8_t tc, u8_t nexth);