diff --git a/mitmproxy/contentviews.py b/mitmproxy/contentviews.py
index 08a7e446f..373c9514e 100644
--- a/mitmproxy/contentviews.py
+++ b/mitmproxy/contentviews.py
@@ -26,9 +26,8 @@ from PIL.ExifTags import TAGS
 import html2text
 import six
 from netlib.odict import ODict
-from netlib import encoding
-import netlib.http.headers
-from netlib.http import url, multipart
+from netlib import encoding, http
+from netlib.http import url
 from netlib.utils import clean_bin, hexdump
 from . import utils
 from .exceptions import ContentViewException
@@ -122,7 +121,7 @@ class ViewAuto(View):
         headers = metadata.get("headers", {})
         ctype = headers.get("content-type")
         if data and ctype:
-            ct = netlib.http.headers.parse_content_type(ctype) if ctype else None
+            ct = http.parse_content_type(ctype) if ctype else None
             ct = "%s/%s" % (ct[0], ct[1])
             if ct in content_types_map:
                 return content_types_map[ct][0](data, **metadata)
@@ -276,7 +275,7 @@ class ViewMultipart(View):
 
     def __call__(self, data, **metadata):
         headers = metadata.get("headers", {})
-        v = multipart.decode(headers, data)
+        v = http.multipart.decode(headers, data)
         if v:
             return "Multipart form", self._format(v)
 
diff --git a/mitmproxy/flow/export.py b/mitmproxy/flow/export.py
index c2f54554d..d71ac6095 100644
--- a/mitmproxy/flow/export.py
+++ b/mitmproxy/flow/export.py
@@ -5,7 +5,6 @@ from textwrap import dedent
 from six.moves.urllib.parse import quote, quote_plus
 
 import netlib.http
-import netlib.http.headers
 
 
 def curl_command(flow):
@@ -88,7 +87,7 @@ def raw_request(flow):
 
 def is_json(headers, content):
     if headers:
-        ct = netlib.http.headers.parse_content_type(headers.get("content-type", ""))
+        ct = netlib.http.parse_content_type(headers.get("content-type", ""))
         if ct and "%s/%s" % (ct[0], ct[1]) == "application/json":
             try:
                 return json.loads(content)
diff --git a/mitmproxy/flow/io_compat.py b/mitmproxy/flow/io_compat.py
index f35b78424..7522163fa 100644
--- a/mitmproxy/flow/io_compat.py
+++ b/mitmproxy/flow/io_compat.py
@@ -65,5 +65,7 @@ def migrate_flow(flow_data):
             flow_data = converters[flow_version](flow_data)
         else:
             v = ".".join(str(i) for i in flow_data["version"])
-            raise ValueError("Incompatible serialized data version: {}".format(v))
+            raise ValueError(
+                "{} cannot read files serialized with version {}.".format(version.NAMEVERSION, v)
+            )
     return flow_data
diff --git a/netlib/http/__init__.py b/netlib/http/__init__.py
index c4eb1d58d..14de26a16 100644
--- a/netlib/http/__init__.py
+++ b/netlib/http/__init__.py
@@ -1,14 +1,14 @@
 from __future__ import absolute_import, print_function, division
 from .request import Request
 from .response import Response
-from .headers import Headers
+from .headers import Headers, parse_content_type
 from .message import decoded
-from . import http1, http2, status_codes
+from . import http1, http2, status_codes, multipart
 
 __all__ = [
     "Request",
     "Response",
-    "Headers",
+    "Headers", "parse_content_type",
     "decoded",
-    "http1", "http2", "status_codes",
+    "http1", "http2", "status_codes", "multipart",
 ]
diff --git a/pathod/language/__init__.py b/pathod/language/__init__.py
index 399baa3e7..0841196e8 100644
--- a/pathod/language/__init__.py
+++ b/pathod/language/__init__.py
@@ -3,6 +3,7 @@ from __future__ import absolute_import
 import itertools
 import time
 
+from six.moves import range
 import pyparsing as pp
 
 from . import http, http2, websockets, writer, exceptions
@@ -19,7 +20,7 @@ __all__ = [
 def expand(msg):
     times = getattr(msg, "times", None)
     if times:
-        for j_ in xrange(int(times.value)):
+        for j_ in range(int(times.value)):
             yield msg.strike_token("times")
     else:
         yield msg
diff --git a/pathod/language/base.py b/pathod/language/base.py
index 97111ed63..1f4edb6f1 100644
--- a/pathod/language/base.py
+++ b/pathod/language/base.py
@@ -3,6 +3,7 @@ import os
 import abc
 import pyparsing as pp
 
+import six
 from six.moves import reduce
 from netlib.utils import escaped_str_to_bytes, bytes_to_escaped_str
 from netlib import human
@@ -341,7 +342,7 @@ class OptionsOrValue(_Component):
         # it to be canonical. The user can specify a different case by using a
         # string value literal.
         self.option_used = False
-        if isinstance(value, basestring):
+        if isinstance(value, six.string_types):
             for i in self.options:
                 # Find the exact option value in a case-insensitive way
                 if i.lower() == value.lower():
diff --git a/test/netlib/http/test_headers.py b/test/netlib/http/test_headers.py
index e12bceaf2..51819b860 100644
--- a/test/netlib/http/test_headers.py
+++ b/test/netlib/http/test_headers.py
@@ -1,5 +1,4 @@
-from netlib.http import Headers
-from netlib.http.headers import parse_content_type
+from netlib.http import Headers, parse_content_type
 from netlib.tutils import raises
 
 
diff --git a/test/pathod/test_language_base.py b/test/pathod/test_language_base.py
index 22355a3ae..47e51bb07 100644
--- a/test/pathod/test_language_base.py
+++ b/test/pathod/test_language_base.py
@@ -41,11 +41,11 @@ class TestTokValueLiteral:
     def test_espr(self):
         v = base.TokValueLiteral("foo")
         assert v.expr()
-        assert v.val == "foo"
+        assert v.val == b"foo"
 
         v = base.TokValueLiteral("foo\n")
         assert v.expr()
-        assert v.val == "foo\n"
+        assert v.val == b"foo\n"
         assert repr(v)
 
     def test_spec(self):
@@ -171,19 +171,19 @@ class TestMisc:
     def test_generators(self):
         v = base.TokValue.parseString("'val'")[0]
         g = v.get_generator({})
-        assert g[:] == "val"
+        assert g[:] == b"val"
 
     def test_value(self):
-        assert base.TokValue.parseString("'val'")[0].val == "val"
-        assert base.TokValue.parseString('"val"')[0].val == "val"
-        assert base.TokValue.parseString('"\'val\'"')[0].val == "'val'"
+        assert base.TokValue.parseString("'val'")[0].val == b"val"
+        assert base.TokValue.parseString('"val"')[0].val == b"val"
+        assert base.TokValue.parseString('"\'val\'"')[0].val == b"'val'"
 
     def test_value2(self):
         class TT(base.Value):
             preamble = "m"
         e = TT.expr()
         v = e.parseString("m'msg'")[0]
-        assert v.value.val == "msg"
+        assert v.value.val == b"msg"
 
         s = v.spec()
         assert s == e.parseString(s)[0].spec()
@@ -235,8 +235,8 @@ class TestKeyValue:
     def test_simple(self):
         e = TKeyValue.expr()
         v = e.parseString("h'foo'='bar'")[0]
-        assert v.key.val == "foo"
-        assert v.value.val == "bar"
+        assert v.key.val == b"foo"
+        assert v.value.val == b"bar"
 
         v2 = e.parseString(v.spec())[0]
         assert v2.key.val == v.key.val
@@ -289,9 +289,9 @@ def test_options_or_value():
             "three"
         ]
     e = TT.expr()
-    assert e.parseString("one")[0].value.val == "one"
-    assert e.parseString("'foo'")[0].value.val == "foo"
-    assert e.parseString("'get'")[0].value.val == "get"
+    assert e.parseString("one")[0].value.val == b"one"
+    assert e.parseString("'foo'")[0].value.val == b"foo"
+    assert e.parseString("'get'")[0].value.val == b"get"
 
     assert e.parseString("one")[0].spec() == "one"
     assert e.parseString("'foo'")[0].spec() == "'foo'"