diff --git a/roles/mail_forwarder/molecule/default/tests/test_optional.py b/roles/mail_forwarder/molecule/default/tests/test_optional.py
index c766603986c3135ced443b1e3483decf43041721..c11e1c6f5aea2b6c9524ad257fca39b2c6536a44 100644
--- a/roles/mail_forwarder/molecule/default/tests/test_optional.py
+++ b/roles/mail_forwarder/molecule/default/tests/test_optional.py
@@ -6,7 +6,7 @@ import testinfra.utils.ansible_runner
 
 
 testinfra_hosts = testinfra.utils.ansible_runner.AnsibleRunner(
-    os.environ['MOLECULE_INVENTORY_FILE']).get_hosts(['parameters-optional'])
+    os.environ['MOLECULE_INVENTORY_FILE']).get_hosts('parameters-optional')
 
 
 def test_smtp_relay_truststore_file(host):