diff --git a/libnetutil/netutil.cc b/libnetutil/netutil.cc
index 240990585..99abc58dd 100644
--- a/libnetutil/netutil.cc
+++ b/libnetutil/netutil.cc
@@ -497,7 +497,7 @@ int ip_is_reserved(struct in_addr *ip)
    returned for the set command. */
 #define MACCACHE_GET 1
 #define MACCACHE_SET 2
-static int do_mac_cache(int command, struct sockaddr_storage *ss, u8 *mac) {
+static int do_mac_cache(int command, const struct sockaddr_storage *ss, u8 *mac) {
   struct MacCache {
     struct sockaddr_storage ip;
     u8 mac[6];
@@ -551,10 +551,10 @@ static int do_mac_cache(int command, struct sockaddr_storage *ss, u8 *mac) {
  * AF_INET. Otherwise the function will return 0 and there would be
  * no way for the caller to tell tell the difference between an error
  * or a cache miss.*/
-int mac_cache_get(struct sockaddr_storage *ss, u8 *mac){
+int mac_cache_get(const struct sockaddr_storage *ss, u8 *mac){
     return do_mac_cache(MACCACHE_GET, ss, mac);
 }
-int mac_cache_set(struct sockaddr_storage *ss, u8 *mac){
+int mac_cache_set(const struct sockaddr_storage *ss, u8 *mac){
     return do_mac_cache(MACCACHE_SET, ss, mac);
 }
 
diff --git a/libnetutil/netutil.h b/libnetutil/netutil.h
index e9c80207e..b51d97fd8 100644
--- a/libnetutil/netutil.h
+++ b/libnetutil/netutil.h
@@ -193,8 +193,8 @@ int ip_is_reserved(struct in_addr *ip);
  * Function mac_cache_set() adds an entry with the given ip (ss) and
  * mac address.  An existing entry for the IP ss will be overwritten
  * with the new MAC address.  mac_cache_set() always returns true. */
-int mac_cache_get(struct sockaddr_storage *ss, u8 *mac);
-int mac_cache_set(struct sockaddr_storage *ss, u8 *mac);
+int mac_cache_get(const struct sockaddr_storage *ss, u8 *mac);
+int mac_cache_set(const struct sockaddr_storage *ss, u8 *mac);
 
 const void *ip_get_data(const void *packet, unsigned int *len,
   struct abstract_ip_hdr *hdr);
diff --git a/tcpip.cc b/tcpip.cc
index 9bcdd6f10..8e2c151b0 100644
--- a/tcpip.cc
+++ b/tcpip.cc
@@ -1949,8 +1949,8 @@ bool setTargetNextHopMAC(Target *target) {
 }
 
 /* Like to getTargetNextHopMAC(), but for arbitrary hosts (not Targets) */
-bool getNextHopMAC(char *iface, u8 *srcmac, struct sockaddr_storage *srcss,
-		   struct sockaddr_storage *dstss, u8 *dstmac)
+bool getNextHopMAC(const char *iface, const u8 *srcmac, const struct sockaddr_storage *srcss,
+		   const struct sockaddr_storage *dstss, u8 *dstmac)
 {
   arp_t *a;
   struct arp_entry ae;
diff --git a/tcpip.h b/tcpip.h
index dcbca2572..41d8c4f94 100644
--- a/tcpip.h
+++ b/tcpip.h
@@ -476,8 +476,8 @@ int setTargetMACIfAvailable(Target *target, struct link_header *linkhdr,
    after an ARP scan if many directly connected machines are involved. */
 bool setTargetNextHopMAC(Target *target);
 
-bool getNextHopMAC(char *iface, u8 *srcmac, struct sockaddr_storage *srcss,
-		   struct sockaddr_storage *dstss, u8 *dstmac);
+bool getNextHopMAC(const char *iface, const u8 *srcmac, const struct sockaddr_storage *srcss,
+		   const struct sockaddr_storage *dstss, u8 *dstmac);