diff --git a/mitmproxy/proxy/config.py b/mitmproxy/proxy/config.py
index 9246fe04d..32d881b05 100644
--- a/mitmproxy/proxy/config.py
+++ b/mitmproxy/proxy/config.py
@@ -199,7 +199,7 @@ def process_proxy_options(parser, options):
                 password_manager = authentication.PassManHtpasswd(
                     options.auth_htpasswd)
             except ValueError as v:
-                return parser.error(v.message)
+                return parser.error(v)
         authenticator = authentication.BasicProxyAuth(password_manager, "mitmproxy")
     else:
         authenticator = authentication.NullProxyAuth(None)
diff --git a/tox.ini b/tox.ini
index 3abd6e4ca..bd2c89120 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,7 +7,7 @@ deps =
   codecov>=2.0.5
 passenv = CI TRAVIS_BUILD_ID TRAVIS TRAVIS_BRANCH TRAVIS_JOB_NUMBER TRAVIS_PULL_REQUEST TRAVIS_JOB_ID TRAVIS_REPO_SLUG TRAVIS_COMMIT
 setenv =
-    PY3TESTS =  test/netlib test/pathod/ test/mitmproxy/script test/mitmproxy/test_contentview.py test/mitmproxy/test_custom_contentview.py test/mitmproxy/test_app.py test/mitmproxy/test_controller.py test/mitmproxy/test_fuzzing.py test/mitmproxy/test_script.py test/mitmproxy/test_web_app.py test/mitmproxy/test_utils.py test/mitmproxy/test_stateobject.py test/mitmproxy/test_cmdline.py test/mitmproxy/test_contrib_tnetstring.py
+    PY3TESTS =  test/netlib test/pathod/ test/mitmproxy/script test/mitmproxy/test_contentview.py test/mitmproxy/test_custom_contentview.py test/mitmproxy/test_app.py test/mitmproxy/test_controller.py test/mitmproxy/test_fuzzing.py test/mitmproxy/test_script.py test/mitmproxy/test_web_app.py test/mitmproxy/test_utils.py test/mitmproxy/test_stateobject.py test/mitmproxy/test_cmdline.py test/mitmproxy/test_contrib_tnetstring.py test/mitmproxy/test_proxy.py
 
 [testenv:py27]
 commands =