diff --git a/src/include/ipv4/lwip/ip.h b/src/include/ipv4/lwip/ip.h
index c631f324..c8b9c222 100644
--- a/src/include/ipv4/lwip/ip.h
+++ b/src/include/ipv4/lwip/ip.h
@@ -43,7 +43,6 @@
 struct netif;
 
 void ip_init(void);
-u8_t ip_lookup(void *header, struct netif *inp);
 struct netif *ip_route(struct ip_addr *dest);
 err_t ip_input(struct pbuf *p, struct netif *inp);
 err_t ip_output(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
diff --git a/src/include/lwip/udp.h b/src/include/lwip/udp.h
index 8a8563c2..0b412fb0 100644
--- a/src/include/lwip/udp.h
+++ b/src/include/lwip/udp.h
@@ -91,7 +91,6 @@ err_t            udp_send       (struct udp_pcb *pcb, struct pbuf *p);
 
 
 /* The following functions are the lower layer interface to UDP. */
-u8_t             udp_lookup     (struct ip_hdr *iphdr, struct netif *inp);
 void             udp_input      (struct pbuf *p, struct netif *inp);
 void             udp_init       (void);