diff --git a/openbsc/src/gsm_subscriber.c b/openbsc/src/gsm_subscriber.c
index a4e35c7..c81b522 100644
--- a/openbsc/src/gsm_subscriber.c
+++ b/openbsc/src/gsm_subscriber.c
@@ -105,7 +105,7 @@
 	case GSM_SUBSCRIBER_UPDATE_DETACHED:
 		/* Only detach if we are currently in this area */
 		if (bts->location_area_code == s->lac)
-			s->lac = 0;
+			s->lac = GSM_LAC_RESERVED_DETACHED;
 		dispatch_signal(SS_SUBSCR, S_SUBSCR_DETACHED, s);
 		break;
 	default: