diff --git a/utils/osmo-auc-gen.c b/utils/osmo-auc-gen.c
index 87960ae..4e07fa7 100644
--- a/utils/osmo-auc-gen.c
+++ b/utils/osmo-auc-gen.c
@@ -138,6 +138,7 @@
 			break;
 		case '3':
 			test_aud.type = OSMO_AUTH_TYPE_UMTS;
+			test_aud.u.umts.ind_bitlen = 5;
 			break;
 		case 'a':
 			rc = osmo_auth_alg_parse(optarg);