diff --git a/tests/test_register.py b/tests/test_register.py
index ce22d3f..d5c5cdd 100644
--- a/tests/test_register.py
+++ b/tests/test_register.py
@@ -1,8 +1,7 @@
 import base64
 from subprocess import CompletedProcess
 
-pfctl_stdout_lines = b'''
-block drop quick proto tcp from <f2b-sendmail-auth> to any port = submission
+pfctl_stdout_lines = b'''block drop quick proto tcp from <f2b-sendmail-auth> to any port = submission
 block drop quick proto tcp from <f2b-sendmail-auth> to any port = smtps
 block drop quick proto tcp from <f2b-sendmail-auth> to any port = smtp
 block drop quick proto tcp from <f2b-sshd> to any port = ssh
@@ -47,7 +46,7 @@ def test_register_valid(client, mocker):
     run_res.stdout = pfctl_stdout_lines
     run_res.check_returncode = noop
 
-    mocker.patch('jail2ban.pfctl.run', return_value=run_res)
+    pfctl_run = mocker.patch('jail2ban.pfctl.run', return_value=run_res)
 
     valid_credentials = base64.b64encode(b"test.example.com:testpassword").decode("utf-8")
     json_payload = {"port":
@@ -58,6 +57,10 @@ def test_register_valid(client, mocker):
                           json=json_payload,
                           headers={"Authorization": "Basic " + valid_credentials})
 
+    pfctl_run_input_arg = pfctl_run.call_args_list[1][1]['input']
+    for existing_line in pfctl_stdout_lines.splitlines():
+        assert existing_line in pfctl_run_input_arg.splitlines()
+
     assert response.json['action'] == 'start'