diff --git a/clock.c b/clock.c
index 4562078..e5d58ba 100644
--- a/clock.c
+++ b/clock.c
@@ -66,6 +66,7 @@ struct clock_subscriber {
 	struct PortIdentity targetPortIdentity;
 	struct address addr;
 	UInteger16 sequenceId;
+	time_t expiration;
 };
 
 struct clock {
@@ -134,10 +135,11 @@ static void remove_subscriber(struct clock_subscriber *s)
 }
 
 static void clock_update_subscription(struct clock *c, struct ptp_message *req,
-				      uint8_t *bitmask)
+				      uint8_t *bitmask, uint16_t duration)
 {
 	struct clock_subscriber *s;
 	int i, remove = 1;
+	struct timespec now;
 
 	for (i = 0; i < EVENT_BITMASK_CNT; i++) {
 		if (bitmask[i]) {
@@ -154,6 +156,8 @@ static void clock_update_subscription(struct clock *c, struct ptp_message *req,
 			if (!remove) {
 				s->addr = req->address;
 				memcpy(s->events, bitmask, EVENT_BITMASK_CNT);
+				clock_gettime(CLOCK_MONOTONIC, &now);
+				s->expiration = now.tv_sec + duration;
 			} else {
 				remove_subscriber(s);
 			}
@@ -171,24 +175,33 @@ static void clock_update_subscription(struct clock *c, struct ptp_message *req,
 	s->targetPortIdentity = req->header.sourcePortIdentity;
 	s->addr = req->address;
 	memcpy(s->events, bitmask, EVENT_BITMASK_CNT);
+	clock_gettime(CLOCK_MONOTONIC, &now);
+	s->expiration = now.tv_sec + duration;
 	s->sequenceId = 0;
 	LIST_INSERT_HEAD(&c->subscribers, s, list);
 }
 
 static void clock_get_subscription(struct clock *c, struct ptp_message *req,
-				   uint8_t *bitmask)
+				   uint8_t *bitmask, uint16_t *duration)
 {
 	struct clock_subscriber *s;
+	struct timespec now;
 
 	LIST_FOREACH(s, &c->subscribers, list) {
 		if (!memcmp(&s->targetPortIdentity, &req->header.sourcePortIdentity,
 			    sizeof(struct PortIdentity))) {
 			memcpy(bitmask, s->events, EVENT_BITMASK_CNT);
+			clock_gettime(CLOCK_MONOTONIC, &now);
+			if (s->expiration < now.tv_sec)
+				*duration = 0;
+			else
+				*duration = s->expiration - now.tv_sec;
 			return;
 		}
 	}
 	/* A client without entry means the client has no subscriptions. */
 	memset(bitmask, 0, EVENT_BITMASK_CNT);
+	*duration = 0;
 }
 
 static void clock_flush_subscriptions(struct clock *c)
@@ -200,6 +213,21 @@ static void clock_flush_subscriptions(struct clock *c)
 	}
 }
 
+static void clock_prune_subscriptions(struct clock *c)
+{
+	struct clock_subscriber *s, *tmp;
+	struct timespec now;
+
+	clock_gettime(CLOCK_MONOTONIC, &now);
+	LIST_FOREACH_SAFE(s, &c->subscribers, list, tmp) {
+		if (s->expiration <= now.tv_sec) {
+			pr_info("subscriber %s timed out",
+				pid2str(&s->targetPortIdentity));
+			remove_subscriber(s);
+		}
+	}
+}
+
 void clock_send_notification(struct clock *c, struct ptp_message *msg,
 			     int msglen, enum notification event)
 {
@@ -410,7 +438,7 @@ static int clock_management_get_response(struct clock *c, struct port *p,
 			break;
 		}
 		sen = (struct subscribe_events_np *)tlv->data;
-		clock_get_subscription(c, req, sen->bitmask);
+		clock_get_subscription(c, req, sen->bitmask, &sen->duration);
 		respond = 1;
 		break;
 	}
@@ -450,7 +478,8 @@ static int clock_management_set(struct clock *c, struct port *p,
 		break;
 	case SUBSCRIBE_EVENTS_NP:
 		sen = (struct subscribe_events_np *)tlv->data;
-		clock_update_subscription(c, req, sen->bitmask);
+		clock_update_subscription(c, req, sen->bitmask,
+					  sen->duration);
 		respond = 1;
 		break;
 	}
@@ -1103,6 +1132,7 @@ int clock_poll(struct clock *c)
 	if (sde)
 		handle_state_decision_event(c);
 
+	clock_prune_subscriptions(c);
 	return 0;
 }
 
diff --git a/tlv.c b/tlv.c
index 430410f..892e4bc 100644
--- a/tlv.c
+++ b/tlv.c
@@ -62,6 +62,7 @@ static int mgt_post_recv(struct management_tlv *m, uint16_t data_len,
 	struct port_ds_np *pdsnp;
 	struct time_status_np *tsn;
 	struct grandmaster_settings_np *gsn;
+	struct subscribe_events_np *sen;
 	struct mgmt_clock_description *cd;
 	int extra_len = 0, len;
 	uint8_t *buf;
@@ -245,6 +246,8 @@ static int mgt_post_recv(struct management_tlv *m, uint16_t data_len,
 	case SUBSCRIBE_EVENTS_NP:
 		if (data_len != sizeof(struct subscribe_events_np))
 			goto bad_length;
+		sen = (struct subscribe_events_np *)m->data;
+		sen->duration = ntohs(sen->duration);
 		break;
 	case SAVE_IN_NON_VOLATILE_STORAGE:
 	case RESET_NON_VOLATILE_STORAGE:
@@ -277,6 +280,7 @@ static void mgt_pre_send(struct management_tlv *m, struct tlv_extra *extra)
 	struct port_ds_np *pdsnp;
 	struct time_status_np *tsn;
 	struct grandmaster_settings_np *gsn;
+	struct subscribe_events_np *sen;
 	struct mgmt_clock_description *cd;
 	switch (m->id) {
 	case CLOCK_DESCRIPTION:
@@ -341,6 +345,10 @@ static void mgt_pre_send(struct management_tlv *m, struct tlv_extra *extra)
 		pdsnp->neighborPropDelayThresh = htonl(pdsnp->neighborPropDelayThresh);
 		pdsnp->asCapable = htonl(pdsnp->asCapable);
 		break;
+	case SUBSCRIBE_EVENTS_NP:
+		sen = (struct subscribe_events_np *)m->data;
+		sen->duration = htons(sen->duration);
+		break;
 	}
 }
 
diff --git a/tlv.h b/tlv.h
index a379baa..e5792ae 100644
--- a/tlv.h
+++ b/tlv.h
@@ -201,6 +201,7 @@ struct port_ds_np {
 #define EVENT_BITMASK_CNT 64
 
 struct subscribe_events_np {
+	uint16_t      duration; /* seconds */
 	uint8_t       bitmask[EVENT_BITMASK_CNT];
 } PACKED;