diff --git a/port.h b/port.h
index 80c543e..0b07d55 100644
--- a/port.h
+++ b/port.h
@@ -210,6 +210,9 @@ struct port *port_open(const char *phc_device,
 		       struct interface *interface,
 		       struct clock *clock);
 
+struct ptp_message *port_signaling_construct(struct port *p,
+					     const struct PortIdentity *tpid);
+
 /**
  * Returns a port's current state.
  * @param port  A port instance.
diff --git a/port_signaling.c b/port_signaling.c
index cbd0cf4..2f5a682 100644
--- a/port_signaling.c
+++ b/port_signaling.c
@@ -30,8 +30,8 @@ const struct PortIdentity wildcard_pid = {
 	.portNumber = 0xffff,
 };
 
-static struct ptp_message *port_signaling_construct(struct port *p,
-						    struct PortIdentity *tpid)
+struct ptp_message *port_signaling_construct(struct port *p,
+					     const struct PortIdentity *tpid)
 {
 	struct ptp_message *msg;