diff --git a/tests/test_subscriber_errors.ctrl b/tests/test_subscriber_errors.ctrl
index 425b0df..8309e61 100644
--- a/tests/test_subscriber_errors.ctrl
+++ b/tests/test_subscriber_errors.ctrl
@@ -114,3 +114,6 @@
 
 SET 50 subscriber.create 901990000000001
 ERROR 50 Subscriber already exists.
+
+SET 51 subscriber.by-imsi-1234567890123456.msisdn hellobadmsisdn
+ERROR 51 Value failed verification.