diff --git a/libnetutil/netutil.cc b/libnetutil/netutil.cc
index 651988fe7..974440e6d 100644
--- a/libnetutil/netutil.cc
+++ b/libnetutil/netutil.cc
@@ -1671,7 +1671,7 @@ int ipaddr2devname(char *dev, const struct sockaddr_storage *addr) {
   return -1;
 }
 
-int devname2ipaddr(char *dev, int af, struct sockaddr_storage *addr) {
+int devname2ipaddr(const char *dev, int af, struct sockaddr_storage *addr) {
   struct interface_info *ifaces;
   int numifaces;
   int i;
diff --git a/libnetutil/netutil.h b/libnetutil/netutil.h
index 3c4488ce7..9deccfbbb 100644
--- a/libnetutil/netutil.h
+++ b/libnetutil/netutil.h
@@ -354,7 +354,7 @@ int ipaddr2devname( char *dev, const struct sockaddr_storage *addr );
 
 /* Convert a network interface name (IE ppp0 eth0) to an IP address.
  * Returns 0 on success or -1 in case of error. */
-int devname2ipaddr(char *dev, int af, struct sockaddr_storage *addr);
+int devname2ipaddr(const char *dev, int af, struct sockaddr_storage *addr);
 
 int sockaddr_equal(const struct sockaddr_storage *a,
   const struct sockaddr_storage *b);