diff --git a/examples/har_extractor.py b/examples/har_extractor.py
index d6b50c213..a5c055192 100644
--- a/examples/har_extractor.py
+++ b/examples/har_extractor.py
@@ -60,6 +60,12 @@ def start(context):
         suit your actual needs of HAR generation. As it will probably be
         necessary to cluster logs by IPs or reset them from time to time.
     """
+    if sys.version_info >= (3, 0):
+        raise RuntimeError(
+            "har_extractor.py does not work on Python 3. "
+            "Please check out https://github.com/mitmproxy/mitmproxy/issues/1320 "
+            "if you want to help making this work again."
+        )
     context.dump_file = None
     if len(sys.argv) > 1:
         context.dump_file = sys.argv[1]
diff --git a/test/mitmproxy/test_examples.py b/test/mitmproxy/test_examples.py
index 22d3c4259..206a03660 100644
--- a/test/mitmproxy/test_examples.py
+++ b/test/mitmproxy/test_examples.py
@@ -1,6 +1,7 @@
 import glob
 import json
 import os
+import sys
 from contextlib import contextmanager
 
 from mitmproxy import script
@@ -133,6 +134,12 @@ def test_redirect_requests():
 
 
 def test_har_extractor():
+    if sys.version_info >= (3, 0):
+        with tutils.raises("does not work on Python 3"):
+            with example("har_extractor.py -"):
+                pass
+        return
+
     with tutils.raises(script.ScriptException):
         with example("har_extractor.py"):
             pass
diff --git a/tox.ini b/tox.ini
index 251609a59..6e9aa3865 100644
--- a/tox.ini
+++ b/tox.ini
@@ -16,7 +16,7 @@ commands =
 
 [testenv:py35]
 setenv =
-  TESTS = 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 test/mitmproxy/test_protocol_http1.py test/mitmproxy/test_platform_pf.py test/mitmproxy/test_server.py test/mitmproxy/test_filt.py test/mitmproxy/test_flow_export.py test/mitmproxy/test_web_master.py test/mitmproxy/test_flow_format_compat.py
+  TESTS = 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 test/mitmproxy/test_protocol_http1.py test/mitmproxy/test_platform_pf.py test/mitmproxy/test_server.py test/mitmproxy/test_filt.py test/mitmproxy/test_flow_export.py test/mitmproxy/test_web_master.py test/mitmproxy/test_flow_format_compat.py test/mitmproxy/test_examples.py
   HOME = {envtmpdir}
 
 [testenv:docs]