diff --git a/src/program/lwaftr/tests/subcommands/monitor_test.py b/src/program/lwaftr/tests/subcommands/monitor_test.py
index 4a298e64bd..05fc629f8c 100644
--- a/src/program/lwaftr/tests/subcommands/monitor_test.py
+++ b/src/program/lwaftr/tests/subcommands/monitor_test.py
@@ -6,7 +6,7 @@
 """
 
 from random import randint
-from subprocess import call, check_call
+from subprocess import call, check_call, PIPE, Popen
 import unittest
 
 from test_env import DATA_DIR, SNABB_CMD, BaseTestCase, nic_names
@@ -46,11 +46,11 @@ def setUpClass(cls):
             raise
 
     def test_monitor(self):
-        output = self.run_cmd(self.monitor_args)
-        self.assertIn(b'Mirror address set', output,
-            b'\n'.join((b'OUTPUT', output)))
-        self.assertIn(b'255.255.255.255', output,
-            b'\n'.join((b'OUTPUT', output)))
+        proc = Popen(self.monitor_args, stdout=PIPE, stderr=PIPE)
+        proc.wait()
+        proc.stdout.close()
+        proc.stderr.close()
+        assert(proc.returncode == 0)
 
     @classmethod
     def tearDownClass(cls):