diff --git a/include/re_sipevent.h b/include/re_sipevent.h
index 0812921..8f60470 100644
--- a/include/re_sipevent.h
+++ b/include/re_sipevent.h
@@ -60,8 +60,9 @@ typedef void (sipevent_close_h)(int err, const struct sip_msg *msg, void *arg);
 int sipevent_accept(struct sipnot **notp, struct sipevent_sock *sock,
 		    const struct sip_msg *msg, struct sip_dialog *dlg,
 		    const struct sipevent_event *event,
-		    uint16_t scode, const char *reason, uint32_t expires_dfl,
-		    uint32_t expires_max, const char *cuser, const char *ctype,
+		    uint16_t scode, const char *reason, uint32_t expires_min,
+		    uint32_t expires_dfl, uint32_t expires_max,
+		    const char *cuser, const char *ctype,
 		    sip_auth_h *authh, void *aarg, bool aref,
 		    sipevent_close_h *closeh, void *arg, const char *fmt, ...);
 int sipevent_notify(struct sipnot *not, struct mbuf *mb, bool term,
diff --git a/src/sipevent/listen.c b/src/sipevent/listen.c
index a4b6434..2224728 100644
--- a/src/sipevent/listen.c
+++ b/src/sipevent/listen.c
@@ -254,6 +254,20 @@ static void subscribe_handler(struct sipevent_sock *sock,
 		return;
 	}
 
+	if (pl_isset(&msg->expires))
+		expires = pl_u32(&msg->expires);
+	else
+		expires = not->expires_dfl;
+
+	if (expires > 0 && expires < not->expires_min) {
+		(void)sip_replyf(sip, msg, 423, "Interval Too Brief",
+				 "Min-Expires: %u\r\n"
+				 "Content-Length: 0\r\n"
+				 "\r\n",
+				 not->expires_min);
+		return;
+	}
+
 	if (!sip_dialog_rseq_valid(not->dlg, msg)) {
 		(void)sip_reply(sip, msg, 500, "Bad Sequence");
 		return;
@@ -261,11 +275,6 @@ static void subscribe_handler(struct sipevent_sock *sock,
 
 	(void)sip_dialog_update(not->dlg, msg);
 
-	if (pl_isset(&msg->expires))
-		expires = pl_u32(&msg->expires);
-	else
-		expires = not->expires_dfl;
-
 	sipnot_refresh(not, expires);
 
 	(void)sipnot_reply(not, msg, 200, "OK");
diff --git a/src/sipevent/notify.c b/src/sipevent/notify.c
index d86dc23..9fb716a 100644
--- a/src/sipevent/notify.c
+++ b/src/sipevent/notify.c
@@ -293,8 +293,9 @@ int sipnot_reply(struct sipnot *not, const struct sip_msg *msg,
 int sipevent_accept(struct sipnot **notp, struct sipevent_sock *sock,
 		    const struct sip_msg *msg, struct sip_dialog *dlg,
 		    const struct sipevent_event *event,
-		    uint16_t scode, const char *reason, uint32_t expires_dfl,
-		    uint32_t expires_max, const char *cuser, const char *ctype,
+		    uint16_t scode, const char *reason, uint32_t expires_min,
+		    uint32_t expires_dfl, uint32_t expires_max,
+		    const char *cuser, const char *ctype,
 		    sip_auth_h *authh, void *aarg, bool aref,
 		    sipevent_close_h *closeh, void *arg, const char *fmt, ...)
 {
@@ -303,7 +304,7 @@ int sipevent_accept(struct sipnot **notp, struct sipevent_sock *sock,
 	int err;
 
 	if (!notp || !sock || !msg || !scode || !reason || !expires_dfl ||
-	    !expires_max || !cuser || !ctype)
+	    !expires_max || !cuser || !ctype || expires_dfl < expires_min)
 		return EINVAL;
 
 	not = mem_zalloc(sizeof(*not), destructor);
@@ -373,6 +374,7 @@ int sipevent_accept(struct sipnot **notp, struct sipevent_sock *sock,
 			goto out;
 	}
 
+	not->expires_min = expires_min;
 	not->expires_dfl = expires_dfl;
 	not->expires_max = expires_max;
 	not->sock   = mem_ref(sock);
diff --git a/src/sipevent/sipevent.h b/src/sipevent/sipevent.h
index d3d122b..1fdef5f 100644
--- a/src/sipevent/sipevent.h
+++ b/src/sipevent/sipevent.h
@@ -35,6 +35,7 @@ struct sipnot {
 	char *ctype;
 	sipevent_close_h *closeh;
 	void *arg;
+	uint32_t expires_min;
 	uint32_t expires_dfl;
 	uint32_t expires_max;
 	enum sipevent_reason reason;