Removed the forward declaration of netif.
diff --git a/src/include/ipv4/lwip/ip_addr.h b/src/include/ipv4/lwip/ip_addr.h
index e76d255..40051a1 100644
--- a/src/include/ipv4/lwip/ip_addr.h
+++ b/src/include/ipv4/lwip/ip_addr.h
@@ -51,8 +51,6 @@
   u32_t s_addr;
 };
 
-struct netif;
-
 extern const struct ip_addr ip_addr_any;
 extern const struct ip_addr ip_addr_broadcast;