diff --git a/src/core/ipv4/ip.c b/src/core/ipv4/ip.c
index f0aad8dd..ceada797 100644
--- a/src/core/ipv4/ip.c
+++ b/src/core/ipv4/ip.c
@@ -62,40 +62,12 @@
  * The interface that provided the packet for the current callback
  * invocation.
  */
-static struct netif *current_netif;
+struct netif *current_netif;
 
 /**
  * Header of the input packet currently being processed.
  */
-static const struct ip_hdr *current_header;
-
-/**
- * Get the interface that received the current packet.
- *
- * This function must only be called from a receive callback (udp_recv,
- * raw_recv, tcp_accept). It will return NULL otherwise.
- *
- * @param pcb Pointer to the pcb receiving a packet.
- */
-struct netif *
-ip_current_netif(void)
-{
-  return current_netif;
-}
-
-/**
- * Get the IP header of the current packet.
- *
- * This function must only be called from a receive callback (udp_recv,
- * raw_recv, tcp_accept). It will return NULL otherwise.
- *
- * @param pcb Pointer to the pcb receiving a packet.
- */
-const struct ip_hdr *
-ip_current_header(void)
-{
-  return current_header;
-}
+const struct ip_hdr *current_header;
 
 /**
  * Finds the appropriate network interface for a given IP address. It
diff --git a/src/include/ipv4/lwip/ip.h b/src/include/ipv4/lwip/ip.h
index 14eba3ca..fd84f304 100644
--- a/src/include/ipv4/lwip/ip.h
+++ b/src/include/ipv4/lwip/ip.h
@@ -153,6 +153,11 @@ PACK_STRUCT_END
 #define IPH_PROTO_SET(hdr, proto) (hdr)->_ttl_proto = (htons((proto) | (IPH_TTL(hdr) << 8)))
 #define IPH_CHKSUM_SET(hdr, chksum) (hdr)->_chksum = (chksum)
 
+/** The interface that provided the packet for the current callback invocation. */
+extern struct netif *current_netif;
+/** Header of the input packet currently being processed. */
+extern const struct ip_hdr *current_header;
+
 #define ip_init() /* Compatibility define, not init needed. */
 struct netif *ip_route(struct ip_addr *dest);
 err_t ip_input(struct pbuf *p, struct netif *inp);
@@ -170,8 +175,14 @@ err_t ip_output_if_opt(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest
        u8_t ttl, u8_t tos, u8_t proto, struct netif *netif, void *ip_options,
        u16_t optlen);
 #endif /* IP_OPTIONS_SEND */
-struct netif *ip_current_netif(void);
-const struct ip_hdr *ip_current_header(void);
+/** Get the interface that received the current packet.
+ * This function must only be called from a receive callback (udp_recv,
+ * raw_recv, tcp_accept). It will return NULL otherwise. */
+#define ip_current_netif()  (current_netif)
+/** Get the IP header of the current packet.
+ * This function must only be called from a receive callback (udp_recv,
+ * raw_recv, tcp_accept). It will return NULL otherwise. */
+#define ip_current_header() (current_header)
 #if IP_DEBUG
 void ip_debug_print(struct pbuf *p);
 #else