diff --git a/bin/tests/system/masterformat/ns1/named.conf b/bin/tests/system/masterformat/ns1/named.conf
index 0968e729e0..d52ef6acfc 100644
--- a/bin/tests/system/masterformat/ns1/named.conf
+++ b/bin/tests/system/masterformat/ns1/named.conf
@@ -27,6 +27,7 @@ options {
 	notify no;
 	dnssec-enable yes;
 	session-keyfile "session.key";
+	servfail-ttl 0;
 };
 
 key rndc_key {
diff --git a/bin/tests/system/masterformat/ns2/named.conf b/bin/tests/system/masterformat/ns2/named.conf
index 8da301ef1f..8307f1f095 100644
--- a/bin/tests/system/masterformat/ns2/named.conf
+++ b/bin/tests/system/masterformat/ns2/named.conf
@@ -26,6 +26,7 @@ options {
 	recursion no;
 	notify no;
 	dnssec-enable yes;
+	servfail-ttl 0;
 };
 
 zone "example" {