diff --git a/include/proto/payload.h b/include/proto/payload.h
index 4b658d4..fd89c88 100644
--- a/include/proto/payload.h
+++ b/include/proto/payload.h
@@ -27,6 +27,7 @@
 #include <types/session.h>
 
 int fetch_rdp_cookie_name(struct session *s, struct sample *smp, const char *cname, int clen);
+int val_payload_lv(struct arg *arg, char **err_msg);
 
 #endif /* _PROTO_PROTO_PAYLOAD_H */