diff --git a/payload.h b/payload.h
index 24484a1db..4b1021b7d 100644
--- a/payload.h
+++ b/payload.h
@@ -89,4 +89,10 @@
 
 /* $Id$ */
 
+#ifndef PAYLOAD_H
+#define PAYLOAD_H
+
 const char *get_udp_payload(u16 dport, size_t *length);
+const char *udp_port2payload(u16 dport, size_t *length);
+
+#endif /* PAYLOAD_H */