diff --git a/bin/tests/system/masterformat/clean.sh b/bin/tests/system/masterformat/clean.sh
index d6245f4688..e0bd3afe32 100755
--- a/bin/tests/system/masterformat/clean.sh
+++ b/bin/tests/system/masterformat/clean.sh
@@ -22,6 +22,7 @@ rm -f ns1/example.db.compat
 rm -f ns1/example.db.serial.raw
 rm -f ns1/large.db ns1/large.db.raw
 rm -f ns1/example.db.map ns1/signed.db.map
+rm -f ns1/session.key
 rm -f dig.out.*
 rm -f dig.out
 rm -f */named.memstats
diff --git a/bin/tests/system/masterformat/ns1/named.conf b/bin/tests/system/masterformat/ns1/named.conf
index 7314075624..03d0e29698 100644
--- a/bin/tests/system/masterformat/ns1/named.conf
+++ b/bin/tests/system/masterformat/ns1/named.conf
@@ -28,6 +28,7 @@ options {
 	recursion no;
 	notify no;
 	dnssec-enable yes;
+	session-keyfile "session.key";
 };
 
 key rndc_key {