diff --git a/core/net/tcpip.c b/core/net/tcpip.c
index fda1b519f..f6184144a 100644
--- a/core/net/tcpip.c
+++ b/core/net/tcpip.c
@@ -570,6 +570,7 @@ tcpip_ipv6_output(void)
 	  PRINTF("FALLBACK: removing ext hdrs & setting proto %d %d\n", 
 		 uip_ext_len, *((uint8_t *)UIP_IP_BUF + 40));
 	  if(uip_ext_len > 0) {
+	    extern void remove_ext_hdr(void);
 	    uint8_t proto = *((uint8_t *)UIP_IP_BUF + 40);
 	    remove_ext_hdr();
 	    /* This should be copied from the ext header... */