diff --git a/miniupnpd/miniupnpd.c b/miniupnpd/miniupnpd.c
index 3629dcb..1c5275d 100644
--- a/miniupnpd/miniupnpd.c
+++ b/miniupnpd/miniupnpd.c
@@ -2060,6 +2060,12 @@ main(int argc, char * * argv)
 			{
 				upnp_event_var_change_notify(EWanIPC);
 			}
+#endif
+#ifdef ENABLE_PCP
+			if(GETFLAG(ENABLENATPMPMASK))
+			{
+				PCPPublicAddressChanged();
+			}
 #endif
 			should_send_public_address_change_notif = 0;
 		}
diff --git a/miniupnpd/pcpserver.c b/miniupnpd/pcpserver.c
index d1742e0..e76d57f 100644
--- a/miniupnpd/pcpserver.c
+++ b/miniupnpd/pcpserver.c
@@ -101,8 +101,10 @@ struct pcp_server_info {
 };
 
 /* default server settings, highest version supported is the default */
-static struct pcp_server_info this_server_info = {2};
+static const struct pcp_server_info this_server_info = {2};
 
+/* origin for "epoch time" sent into responses */
+time_t epoch_origin = 0;
 
 /* structure holding information from PCP msg*/
 /* all variables are in host byte order except IP addresses */
@@ -1448,7 +1450,10 @@ static void createPCPResponse(unsigned char *response, pcp_info_t *pcp_msg_info)
 
 	response[1] |= 0x80;	/* r_opcode */
 	response[3] = pcp_msg_info->result_code;
-	WRITENU32(response + 8, time(NULL) - startup_time); /* epochtime */
+	if(epoch_origin == 0) {
+		epoch_origin = startup_time;
+	}
+	WRITENU32(response + 8, time(NULL) - epoch_origin); /* epochtime */
 	switch (pcp_msg_info->result_code) {
 	/*long lifetime errors*/
 	case PCP_ERR_UNSUPP_VERSION:
@@ -1633,4 +1638,12 @@ int OpenAndConfPCPv6Socket(void)
 	return s;
 }
 #endif /*ENABLE_IPV6*/
+
+void PCPPublicAddressChanged(void)
+{
+	/* according to RFC 6887  8.5 :
+	 *   if the external IP address(es) of the NAT (controlled by
+	 *   the PCP server) changes, the Epoch time MUST be reset. */
+	epoch_origin = time(NULL);
+}
 #endif /*ENABLE_PCP*/
diff --git a/miniupnpd/pcpserver.h b/miniupnpd/pcpserver.h
index 71a4fc4..7974c22 100644
--- a/miniupnpd/pcpserver.h
+++ b/miniupnpd/pcpserver.h
@@ -52,4 +52,10 @@ int ProcessIncomingPCPPacket(int s, unsigned char *msg_buff, int len,
  */
 int OpenAndConfPCPv6Socket(void);
 
+
+/*
+ * To be called when Public IP address changed (IPv4)
+ */
+void PCPPublicAddressChanged(void);
+
 #endif /* PCPSERVER_H_INCLUDED */