diff --git a/lstab.c b/lstab.c
index 72c02e8e..881b5d34 100644
--- a/lstab.c
+++ b/lstab.c
@@ -182,10 +182,6 @@ enum lstab_result lstab_utc2tai(struct lstab *lstab, uint64_t utctime,
 {
 	int epoch = -1, index, next;
 
-	if (utctime > lstab->expiration_utc) {
-		return LSTAB_UNKNOWN;
-	}
-
 	for (index = lstab->length - 1; index > -1; index--) {
 		if (utctime >= lstab->lstab[index].utc) {
 			epoch = index;
@@ -203,5 +199,10 @@ enum lstab_result lstab_utc2tai(struct lstab *lstab, uint64_t utctime,
 	if (next < lstab->length && utctime == lstab->lstab[next].utc - 1) {
 		return LSTAB_AMBIGUOUS;
 	}
+
+	if (utctime > lstab->expiration_utc) {
+		return LSTAB_EXPIRED;
+	}
+
 	return LSTAB_OK;
 }
diff --git a/lstab.h b/lstab.h
index d2393b4b..3811aedd 100644
--- a/lstab.h
+++ b/lstab.h
@@ -41,6 +41,12 @@ enum lstab_result {
 	 */
 	LSTAB_UNKNOWN,
 
+	/**
+	 * The given lstab is past its expiry date and the tai_offset return
+	 * value may not be correct.
+	 */
+	LSTAB_EXPIRED,
+
 	/**
 	 * The given UTC value is ambiguous.  The corresponding TAI time is either
 	 *
diff --git a/ts2phc_nmea_pps_source.c b/ts2phc_nmea_pps_source.c
index db8b5c62..8ea26bf4 100644
--- a/ts2phc_nmea_pps_source.c
+++ b/ts2phc_nmea_pps_source.c
@@ -188,7 +188,7 @@ static int ts2phc_nmea_pps_source_getppstime(struct ts2phc_pps_source *src,
 	struct ts2phc_nmea_pps_source *m =
 		container_of(src, struct ts2phc_nmea_pps_source, pps_source);
 	tmv_t delay_t1, delay_t2, duration_since_rmc, local_t1, local_t2, rmc;
-	int lstab_error = 0, tai_offset = 0;
+	int lstab_error = -1, tai_offset = 0;
 	enum lstab_result result;
 	struct timespec now;
 	int64_t utc_time;
@@ -237,11 +237,12 @@ static int ts2phc_nmea_pps_source_getppstime(struct ts2phc_pps_source *src,
 		break;
 	case LSTAB_UNKNOWN:
 		pr_err("nmea: unable to find utc time in leap second table");
-		lstab_error = -1;
+		break;
+	case LSTAB_EXPIRED:
+		pr_err("nmea: utc time is past leap second table expiry date");
 		break;
 	case LSTAB_AMBIGUOUS:
 		pr_err("nmea: utc time stamp is ambiguous");
-		lstab_error = -1;
 		break;
 	}
 	ts->tv_sec += tai_offset;