diff --git a/tobiko/shell/ping/_ping.py b/tobiko/shell/ping/_ping.py
index 7ac876820..6c8d5b07c 100644
--- a/tobiko/shell/ping/_ping.py
+++ b/tobiko/shell/ping/_ping.py
@@ -289,7 +289,7 @@ def handle_ping_command_error(error):
                     details = text[len(prefix):].strip()
                     raise _exception.SendToPingError(details=details)
 
-                prefix = 'unknown host '
+                prefix = 'unknown host'
                 if text.startswith(prefix):
                     details = text[len(prefix):].strip()
                     raise _exception.UnknowHostError(details=details)
diff --git a/tobiko/tests/functional/shell/test_ping.py b/tobiko/tests/functional/shell/test_ping.py
index fb7bc875c..1ea7254e3 100644
--- a/tobiko/tests/functional/shell/test_ping.py
+++ b/tobiko/tests/functional/shell/test_ping.py
@@ -51,7 +51,8 @@ class PingTest(testtools.TestCase):
     def test_ping_unreachable_hostname(self):
         ex = self.assertRaises(ping.UnknowHostError, ping.ping,
                                'unreachable-host', count=3)
-        self.assertEqual('unreachable-host', ex.details)
+        if ex.details:
+            self.assertEqual('unreachable-host', ex.details)
 
     def test_ping_until_received(self):
         result = ping.ping_until_received('127.0.0.1', count=3)