diff --git a/letsencrypt/tests/errors_test.py b/letsencrypt/tests/errors_test.py
index a99d84719..5da7c0b7a 100644
--- a/letsencrypt/tests/errors_test.py
+++ b/letsencrypt/tests/errors_test.py
@@ -1,6 +1,8 @@
 """Tests for letsencrypt.errors."""
 import unittest
 
+import mock
+
 from acme import messages
 
 from letsencrypt import achallenges
@@ -22,5 +24,21 @@ class FaiiledChallengesTest(unittest.TestCase):
             "Failed authorization procedure. example.com (dns): tls"))
 
 
+class StandaloneBindErrorTest(unittest.TestCase):
+    """Tests for letsencrypt.errors.StandaloneBindError."""
+
+    def setUp(self):
+        from letsencrypt.errors import StandaloneBindError
+        self.error = StandaloneBindError(mock.sentinel.error, 1234)
+
+    def test_instance_args(self):
+        self.assertEqual(mock.sentinel.error, self.error.socket_error)
+        self.assertEqual(1234, self.error.port)
+
+    def test_str(self):
+        self.assertTrue(str(self.error).startswith(
+            "Problem binding to port 1234: "))
+
+
 if __name__ == "__main__":
     unittest.main()  # pragma: no cover