diff --git a/src/hlr.c b/src/hlr.c
index ef008f0..bcae3b5 100644
--- a/src/hlr.c
+++ b/src/hlr.c
@@ -71,6 +71,7 @@
 		gsup_out.message_type = OSMO_GSUP_MSGT_SEND_AUTH_INFO_ERROR;
 		switch (rc) {
 		case 0:
+		case -ENOENT:
 			gsup_out.cause = GMM_CAUSE_IMSI_UNKNOWN;
 			break;
 		default: