diff --git a/docs/features/responsestreaming.rst b/docs/features/responsestreaming.rst
index 8975c1f80..9dc27bf48 100644
--- a/docs/features/responsestreaming.rst
+++ b/docs/features/responsestreaming.rst
@@ -48,8 +48,7 @@ Implementation Details
 ----------------------
 
 When response streaming is enabled, portions of the code which would have otherwise performed
-changes on the response body will see an empty response body instead
-(:py:data:`netlib.http.CONTENT_MISSING`). Any modifications will be ignored.
+changes on the response body will see an empty response body. Any modifications will be ignored.
 
 Streamed responses are usually sent in chunks of 4096 bytes. If the response is sent with a
 ``Transfer-Encoding: chunked`` header, the response will be streamed one chunk at a time.
diff --git a/mitmproxy/console/common.py b/mitmproxy/console/common.py
index 27e6b6dba..141735efe 100644
--- a/mitmproxy/console/common.py
+++ b/mitmproxy/console/common.py
@@ -4,7 +4,6 @@ import urwid
 import urwid.util
 import os
 
-from netlib.http import CONTENT_MISSING
 import netlib.utils
 
 from .. import utils
@@ -256,7 +255,7 @@ def copy_flow_format_data(part, scope, flow):
     else:
         data = ""
         if scope in ("q", "a"):
-            if flow.request.content is None or flow.request.content == CONTENT_MISSING:
+            if flow.request.content is None:
                 return None, "Request content is missing"
             with decoded(flow.request):
                 if part == "h":
@@ -269,7 +268,7 @@ def copy_flow_format_data(part, scope, flow):
             # Add padding between request and response
             data += "\r\n" * 2
         if scope in ("s", "a") and flow.response:
-            if flow.response.content is None or flow.response.content == CONTENT_MISSING:
+            if flow.response.content is None:
                 return None, "Response content is missing"
             with decoded(flow.response):
                 if part == "h":
@@ -420,7 +419,7 @@ def format_flow(f, focus, extended=False, hostheader=False, marked=False):
     if f.response:
         if f.response.content:
             contentdesc = netlib.utils.pretty_size(len(f.response.content))
-        elif f.response.content == CONTENT_MISSING:
+        elif f.response.content is None:
             contentdesc = "[content missing]"
         else:
             contentdesc = "[no content]"
diff --git a/mitmproxy/console/flowview.py b/mitmproxy/console/flowview.py
index ba2aad6aa..b761a9244 100644
--- a/mitmproxy/console/flowview.py
+++ b/mitmproxy/console/flowview.py
@@ -7,7 +7,7 @@ import math
 import urwid
 
 from netlib import odict
-from netlib.http import CONTENT_MISSING, Headers
+from netlib.http import Headers
 from . import common, grideditor, signals, searchable, tabs
 from . import flowdetailview
 from .. import utils, controller, contentviews
@@ -169,7 +169,7 @@ class FlowView(tabs.Tabs):
             self.show()
 
     def content_view(self, viewmode, message):
-        if message.content == CONTENT_MISSING:
+        if message.content is None:
             msg, body = "", [urwid.Text([("error", "[content missing]")])]
             return msg, body
         else:
@@ -510,7 +510,7 @@ class FlowView(tabs.Tabs):
 
     def delete_body(self, t):
         if t == "m":
-            val = CONTENT_MISSING
+            val = None
         else:
             val = None
         if self.tab_offset == TAB_REQ:
diff --git a/mitmproxy/dump.py b/mitmproxy/dump.py
index 7b4609b49..631e4d2e9 100644
--- a/mitmproxy/dump.py
+++ b/mitmproxy/dump.py
@@ -5,7 +5,6 @@ import click
 import itertools
 
 from netlib import tcp
-from netlib.http import CONTENT_MISSING
 import netlib.utils
 from . import flow, filt, contentviews
 from .exceptions import ContentViewException
@@ -180,7 +179,7 @@ class DumpMaster(flow.FlowMaster):
             )
             self.echo(headers, indent=4)
         if self.o.flow_detail >= 3:
-            if message.content == CONTENT_MISSING:
+            if message.content is None:
                 self.echo("(content missing)", indent=4)
             elif message.content:
                 self.echo("")
@@ -283,7 +282,7 @@ class DumpMaster(flow.FlowMaster):
         code = click.style(str(code), fg=code_color, bold=True, blink=(code == 418))
         reason = click.style(flow.response.reason, fg=code_color, bold=True)
 
-        if flow.response.content == CONTENT_MISSING:
+        if flow.response.content is None:
             size = "(content missing)"
         else:
             size = netlib.utils.pretty_size(len(flow.response.content))
diff --git a/mitmproxy/flow.py b/mitmproxy/flow.py
index d656bc4db..fbf102b51 100644
--- a/mitmproxy/flow.py
+++ b/mitmproxy/flow.py
@@ -16,7 +16,7 @@ from six.moves import urllib
 
 from netlib import wsgi
 from netlib.exceptions import HttpException
-from netlib.http import CONTENT_MISSING, Headers, http1
+from netlib.http import Headers, http1
 from . import controller, tnetstring, filt, script, version, flow_format_compat
 from .onboarding import app
 from .proxy.config import HostMatcher
@@ -942,7 +942,7 @@ class FlowMaster(controller.Master):
             return "Can't replay live request."
         if f.intercepted:
             return "Can't replay while intercepting..."
-        if f.request.content == CONTENT_MISSING:
+        if f.request.content is None:
             return "Can't replay request with missing content..."
         if f.request:
             f.backup()
diff --git a/mitmproxy/models/http.py b/mitmproxy/models/http.py
index a80e11b03..40460182e 100644
--- a/mitmproxy/models/http.py
+++ b/mitmproxy/models/http.py
@@ -84,9 +84,8 @@ class HTTPRequest(MessageMixin, Request):
 
         headers: Headers object
 
-        content: Content of the request, None, or CONTENT_MISSING if there
-        is content associated, but not present. CONTENT_MISSING evaluates
-        to False to make checking for the presence of content natural.
+        content: Content of the request, the value is None if there is content
+        associated, but not present.
 
         form_in: The request form which mitmproxy has received. The following
         values are possible:
@@ -226,9 +225,8 @@ class HTTPResponse(MessageMixin, Response):
 
         headers: Headers object
 
-        content: Content of the request, None, or CONTENT_MISSING if there
-        is content associated, but not present. CONTENT_MISSING evaluates
-        to False to make checking for the presence of content natural.
+        content: Content of the response, the value is None if there is content
+        associated, but not present.
 
         timestamp_start: Timestamp indicating when request transmission started
 
diff --git a/mitmproxy/protocol/http.py b/mitmproxy/protocol/http.py
index a2745eac7..56c5f9ea4 100644
--- a/mitmproxy/protocol/http.py
+++ b/mitmproxy/protocol/http.py
@@ -6,7 +6,7 @@ import six
 
 from netlib import tcp
 from netlib.exceptions import HttpException, HttpReadDisconnect, NetlibException
-from netlib.http import Headers, CONTENT_MISSING
+from netlib.http import Headers
 
 from h2.exceptions import H2Error
 
@@ -50,8 +50,8 @@ class _HttpTransmissionLayer(Layer):
         yield "this is a generator"  # pragma: no cover
 
     def send_response(self, response):
-        if response.content == CONTENT_MISSING:
-            raise HttpException("Cannot assemble flow with CONTENT_MISSING")
+        if response.content is None:
+            raise HttpException("Cannot assemble flow with missing content")
         self.send_response_headers(response)
         self.send_response_body(response, [response.content])
 
@@ -231,7 +231,8 @@ class HttpLayer(Layer):
                     six.reraise(ProtocolException, ProtocolException(
                         "Error in HTTP connection: %s" % repr(e)), sys.exc_info()[2])
             finally:
-                flow.live = False
+                if flow:
+                    flow.live = False
 
     def get_request_from_client(self):
         request = self.read_request()
@@ -318,7 +319,7 @@ class HttpLayer(Layer):
             raise Kill()
 
         if flow.response.stream:
-            flow.response.data.content = CONTENT_MISSING
+            flow.response.data.content = None
         else:
             flow.response.data.content = b"".join(self.read_response_body(
                 flow.request,
diff --git a/mitmproxy/script/script.py b/mitmproxy/script/script.py
index f142daca1..5a8334c46 100644
--- a/mitmproxy/script/script.py
+++ b/mitmproxy/script/script.py
@@ -47,7 +47,7 @@ class Script(object):
         if os.name == "nt":  # pragma: no cover
             backslashes = shlex.split(command, posix=False)[0].count("\\")
             command = command.replace("\\", "\\\\", backslashes)
-        args = shlex.split(command)  # pragma: nocover
+        args = shlex.split(command)  # pragma: no cover
         args[0] = os.path.expanduser(args[0])
         if not os.path.exists(args[0]):
             raise ScriptException(
diff --git a/mitmproxy/web/app.py b/mitmproxy/web/app.py
index 2cac2ab9e..cf3c8bdd9 100644
--- a/mitmproxy/web/app.py
+++ b/mitmproxy/web/app.py
@@ -8,7 +8,6 @@ import logging
 import json
 import base64
 
-from netlib.http import CONTENT_MISSING
 from .. import version, filt
 
 
@@ -26,10 +25,8 @@ def _strip_content(flow_state):
                 continue
             if message["content"]:
                 message["contentLength"] = len(message["content"])
-            elif message["content"] == CONTENT_MISSING:
-                message["contentLength"] = None
             else:
-                message["contentLength"] = 0
+                message["contentLength"] = None
             del message["content"]
 
     if "backup" in flow_state:
diff --git a/netlib/http/__init__.py b/netlib/http/__init__.py
index fd632cd5f..917080f7a 100644
--- a/netlib/http/__init__.py
+++ b/netlib/http/__init__.py
@@ -2,13 +2,13 @@ from __future__ import absolute_import, print_function, division
 from .request import Request
 from .response import Response
 from .headers import Headers
-from .message import decoded, CONTENT_MISSING
+from .message import decoded
 from . import http1, http2
 
 __all__ = [
     "Request",
     "Response",
     "Headers",
-    "decoded", "CONTENT_MISSING",
+    "decoded",
     "http1", "http2",
 ]
diff --git a/netlib/http/authentication.py b/netlib/http/authentication.py
index d769abe54..6db70fdd2 100644
--- a/netlib/http/authentication.py
+++ b/netlib/http/authentication.py
@@ -140,7 +140,7 @@ class AuthAction(Action):
         authenticator = BasicProxyAuth(passman, "mitmproxy")
         setattr(namespace, self.dest, authenticator)
 
-    def getPasswordManager(self, s):  # pragma: nocover
+    def getPasswordManager(self, s):  # pragma: no cover
         raise NotImplementedError()
 
 
diff --git a/netlib/http/headers.py b/netlib/http/headers.py
index 784047964..9b8fdae4a 100644
--- a/netlib/http/headers.py
+++ b/netlib/http/headers.py
@@ -8,7 +8,7 @@ from __future__ import absolute_import, print_function, division
 import copy
 try:
     from collections.abc import MutableMapping
-except ImportError:  # pragma: nocover
+except ImportError:  # pragma: no cover
     from collections import MutableMapping  # Workaround for Python < 3.3
 
 
@@ -16,7 +16,7 @@ import six
 
 from netlib.utils import always_byte_args, always_bytes, Serializable
 
-if six.PY2:  # pragma: nocover
+if six.PY2:  # pragma: no cover
     _native = lambda x: x
     _always_bytes = lambda x: x
     _always_byte_args = lambda x: x
@@ -106,7 +106,7 @@ class Headers(MutableMapping, Serializable):
         else:
             return b""
 
-    if six.PY2:  # pragma: nocover
+    if six.PY2:  # pragma: no cover
         __str__ = __bytes__
 
     @_always_byte_args
diff --git a/netlib/http/http1/assemble.py b/netlib/http/http1/assemble.py
index 785ee8d3e..f06ad5a10 100644
--- a/netlib/http/http1/assemble.py
+++ b/netlib/http/http1/assemble.py
@@ -3,12 +3,10 @@ from __future__ import absolute_import, print_function, division
 from ... import utils
 import itertools
 from ...exceptions import HttpException
-from .. import CONTENT_MISSING
-
 
 def assemble_request(request):
-    if request.content == CONTENT_MISSING:
-        raise HttpException("Cannot assemble flow with CONTENT_MISSING")
+    if request.content is None:
+        raise HttpException("Cannot assemble flow with missing content")
     head = assemble_request_head(request)
     body = b"".join(assemble_body(request.data.headers, [request.data.content]))
     return head + body
@@ -21,8 +19,8 @@ def assemble_request_head(request):
 
 
 def assemble_response(response):
-    if response.content == CONTENT_MISSING:
-        raise HttpException("Cannot assemble flow with CONTENT_MISSING")
+    if response.content is None:
+        raise HttpException("Cannot assemble flow with missing content")
     head = assemble_response_head(response)
     body = b"".join(assemble_body(response.data.headers, [response.data.content]))
     return head + body
diff --git a/netlib/http/message.py b/netlib/http/message.py
index e3d8ce375..b6d846baa 100644
--- a/netlib/http/message.py
+++ b/netlib/http/message.py
@@ -7,9 +7,7 @@ import six
 from .headers import Headers
 from .. import encoding, utils
 
-CONTENT_MISSING = 0
-
-if six.PY2:  # pragma: nocover
+if six.PY2:  # pragma: no cover
     _native = lambda x: x
     _always_bytes = lambda x: x
 else:
@@ -182,12 +180,12 @@ class Message(utils.Serializable):
     # Legacy
 
     @property
-    def body(self):  # pragma: nocover
+    def body(self):  # pragma: no cover
         warnings.warn(".body is deprecated, use .content instead.", DeprecationWarning)
         return self.content
 
     @body.setter
-    def body(self, body):  # pragma: nocover
+    def body(self, body):  # pragma: no cover
         warnings.warn(".body is deprecated, use .content instead.", DeprecationWarning)
         self.content = body
 
diff --git a/netlib/http/request.py b/netlib/http/request.py
index 1a9b6f18f..d35c1874e 100644
--- a/netlib/http/request.py
+++ b/netlib/http/request.py
@@ -100,7 +100,7 @@ class Request(Message):
         Setting the host attribute also updates the host header, if present.
         """
 
-        if six.PY2:  # pragma: nocover
+        if six.PY2:  # pragma: no cover
             return self.data.host
 
         if not self.data.host:
@@ -324,59 +324,59 @@ class Request(Message):
 
     # Legacy
 
-    def get_cookies(self):  # pragma: nocover
+    def get_cookies(self):  # pragma: no cover
         warnings.warn(".get_cookies is deprecated, use .cookies instead.", DeprecationWarning)
         return self.cookies
 
-    def set_cookies(self, odict):  # pragma: nocover
+    def set_cookies(self, odict):  # pragma: no cover
         warnings.warn(".set_cookies is deprecated, use .cookies instead.", DeprecationWarning)
         self.cookies = odict
 
-    def get_query(self):  # pragma: nocover
+    def get_query(self):  # pragma: no cover
         warnings.warn(".get_query is deprecated, use .query instead.", DeprecationWarning)
         return self.query or ODict([])
 
-    def set_query(self, odict):  # pragma: nocover
+    def set_query(self, odict):  # pragma: no cover
         warnings.warn(".set_query is deprecated, use .query instead.", DeprecationWarning)
         self.query = odict
 
-    def get_path_components(self):  # pragma: nocover
+    def get_path_components(self):  # pragma: no cover
         warnings.warn(".get_path_components is deprecated, use .path_components instead.", DeprecationWarning)
         return self.path_components
 
-    def set_path_components(self, lst):  # pragma: nocover
+    def set_path_components(self, lst):  # pragma: no cover
         warnings.warn(".set_path_components is deprecated, use .path_components instead.", DeprecationWarning)
         self.path_components = lst
 
-    def get_form_urlencoded(self):  # pragma: nocover
+    def get_form_urlencoded(self):  # pragma: no cover
         warnings.warn(".get_form_urlencoded is deprecated, use .urlencoded_form instead.", DeprecationWarning)
         return self.urlencoded_form or ODict([])
 
-    def set_form_urlencoded(self, odict):  # pragma: nocover
+    def set_form_urlencoded(self, odict):  # pragma: no cover
         warnings.warn(".set_form_urlencoded is deprecated, use .urlencoded_form instead.", DeprecationWarning)
         self.urlencoded_form = odict
 
-    def get_form_multipart(self):  # pragma: nocover
+    def get_form_multipart(self):  # pragma: no cover
         warnings.warn(".get_form_multipart is deprecated, use .multipart_form instead.", DeprecationWarning)
         return self.multipart_form or ODict([])
 
     @property
-    def form_in(self):  # pragma: nocover
+    def form_in(self):  # pragma: no cover
         warnings.warn(".form_in is deprecated, use .first_line_format instead.", DeprecationWarning)
         return self.first_line_format
 
     @form_in.setter
-    def form_in(self, form_in):  # pragma: nocover
+    def form_in(self, form_in):  # pragma: no cover
         warnings.warn(".form_in is deprecated, use .first_line_format instead.", DeprecationWarning)
         self.first_line_format = form_in
 
     @property
-    def form_out(self):  # pragma: nocover
+    def form_out(self):  # pragma: no cover
         warnings.warn(".form_out is deprecated, use .first_line_format instead.", DeprecationWarning)
         return self.first_line_format
 
     @form_out.setter
-    def form_out(self, form_out):  # pragma: nocover
+    def form_out(self, form_out):  # pragma: no cover
         warnings.warn(".form_out is deprecated, use .first_line_format instead.", DeprecationWarning)
         self.first_line_format = form_out
 
diff --git a/netlib/http/response.py b/netlib/http/response.py
index 8f4d62158..da2c81421 100644
--- a/netlib/http/response.py
+++ b/netlib/http/response.py
@@ -97,20 +97,20 @@ class Response(Message):
 
     # Legacy
 
-    def get_cookies(self):  # pragma: nocover
+    def get_cookies(self):  # pragma: no cover
         warnings.warn(".get_cookies is deprecated, use .cookies instead.", DeprecationWarning)
         return self.cookies
 
-    def set_cookies(self, odict):  # pragma: nocover
+    def set_cookies(self, odict):  # pragma: no cover
         warnings.warn(".set_cookies is deprecated, use .cookies instead.", DeprecationWarning)
         self.cookies = odict
 
     @property
-    def msg(self):  # pragma: nocover
+    def msg(self):  # pragma: no cover
         warnings.warn(".msg is deprecated, use .reason instead.", DeprecationWarning)
         return self.reason
 
     @msg.setter
-    def msg(self, reason):  # pragma: nocover
+    def msg(self, reason):  # pragma: no cover
         warnings.warn(".msg is deprecated, use .reason instead.", DeprecationWarning)
         self.reason = reason
diff --git a/pathod/pathoc.py b/pathod/pathoc.py
index 86661f98e..0e6d3ca74 100644
--- a/pathod/pathoc.py
+++ b/pathod/pathoc.py
@@ -208,7 +208,7 @@ class Pathoc(tcp.TCPClient):
         self.ws_framereader = None
 
         if self.use_http2:
-            if not tcp.HAS_ALPN:  # pragma: nocover
+            if not tcp.HAS_ALPN:  # pragma: no cover
                 log.write_raw(
                     self.fp,
                     "HTTP/2 requires ALPN support. "
@@ -458,7 +458,7 @@ class Pathoc(tcp.TCPClient):
             # TODO: do something
 
 
-def main(args):  # pragma: nocover
+def main(args):  # pragma: no cover
     memo = set([])
     trycount = 0
     p = None
diff --git a/pathod/pathoc_cmdline.py b/pathod/pathoc_cmdline.py
index bf827a9aa..b59704f3a 100644
--- a/pathod/pathoc_cmdline.py
+++ b/pathod/pathoc_cmdline.py
@@ -221,6 +221,6 @@ def args_pathoc(argv, stdout=sys.stdout, stderr=sys.stderr):
     return args
 
 
-def go_pathoc():  # pragma: nocover
+def go_pathoc():  # pragma: no cover
     args = args_pathoc(sys.argv)
     pathoc.main(args)
diff --git a/pathod/pathod.py b/pathod/pathod.py
index 55e75074f..b80da8875 100644
--- a/pathod/pathod.py
+++ b/pathod/pathod.py
@@ -430,7 +430,7 @@ class Pathod(tcp.TCPServer):
         return self.log
 
 
-def main(args):  # pragma: nocover
+def main(args):  # pragma: no cover
     ssloptions = SSLOptions(
         cn=args.cn,
         confdir=args.confdir,
diff --git a/pathod/pathod_cmdline.py b/pathod/pathod_cmdline.py
index c92722494..1f972a491 100644
--- a/pathod/pathod_cmdline.py
+++ b/pathod/pathod_cmdline.py
@@ -226,6 +226,6 @@ def args_pathod(argv, stdout_=sys.stdout, stderr_=sys.stderr):
     return args
 
 
-def go_pathod():  # pragma: nocover
+def go_pathod():  # pragma: no cover
     args = args_pathod(sys.argv)
     pathod.main(args)
diff --git a/pathod/utils.py b/pathod/utils.py
index a1109a3c4..1e5bd9a46 100644
--- a/pathod/utils.py
+++ b/pathod/utils.py
@@ -98,7 +98,7 @@ class Data(object):
 data = Data(__name__)
 
 
-def daemonize(stdin='/dev/null', stdout='/dev/null', stderr='/dev/null'):  # pragma: nocover
+def daemonize(stdin='/dev/null', stdout='/dev/null', stderr='/dev/null'):  # pragma: no cover
     try:
         pid = os.fork()
         if pid > 0:
diff --git a/setup.cfg b/setup.cfg
index 96b23026c..7849ca079 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -9,7 +9,7 @@ ignore = E251
 
 [pytest]
 testpaths = test
-addopts = --timeout 30 -s
+addopts = --timeout 60 --capture=no
 
 [coverage:run]
 branch = True
@@ -19,6 +19,5 @@ omit = *contrib*, *tnetstring*, *platform*, *console*, *main.py
 [coverage:report]
 show_missing = True
 exclude_lines =
-    pragma: nocover
     pragma: no cover
     raise NotImplementedError()
diff --git a/test/mitmproxy/test_dump.py b/test/mitmproxy/test_dump.py
index 2228a7320..7e7728814 100644
--- a/test/mitmproxy/test_dump.py
+++ b/test/mitmproxy/test_dump.py
@@ -4,7 +4,6 @@ from mitmproxy.exceptions import ContentViewException
 from mitmproxy.models import HTTPResponse
 
 import netlib.tutils
-from netlib.http import CONTENT_MISSING
 
 from mitmproxy import dump, flow
 from mitmproxy.proxy import Log
@@ -38,7 +37,7 @@ def test_strfuncs():
     flow.request.stickycookie = True
     flow.client_conn = mock.MagicMock()
     flow.client_conn.address.host = "foo"
-    flow.response = netlib.tutils.tresp(content=CONTENT_MISSING)
+    flow.response = netlib.tutils.tresp(content=None)
     flow.response.is_replay = True
     flow.response.status_code = 300
     m.echo_flow(flow)
@@ -104,10 +103,10 @@ class TestDumpMaster:
         o = dump.Options(flow_detail=3)
         m = dump.DumpMaster(None, o, outfile=cs)
         f = tutils.tflow()
-        f.request.content = CONTENT_MISSING
+        f.request.content = None
         m.handle_request(f)
         f.response = HTTPResponse.wrap(netlib.tutils.tresp())
-        f.response.content = CONTENT_MISSING
+        f.response.content = None
         m.handle_response(f)
         assert "content missing" in cs.getvalue()
 
diff --git a/test/mitmproxy/test_flow.py b/test/mitmproxy/test_flow.py
index 33d2b8f91..2353935bf 100644
--- a/test/mitmproxy/test_flow.py
+++ b/test/mitmproxy/test_flow.py
@@ -8,7 +8,7 @@ import mock
 
 import netlib.utils
 from netlib import odict
-from netlib.http import CONTENT_MISSING, Headers
+from netlib.http import Headers
 from mitmproxy import filt, controller, tnetstring, flow
 from mitmproxy.models import Error
 from mitmproxy.models import Flow
@@ -465,7 +465,7 @@ class TestFlow(object):
 
     def test_replace_no_content(self):
         f = tutils.tflow()
-        f.request.content = CONTENT_MISSING
+        f.request.content = None
         assert f.replace("foo", "bar") == 0
 
     def test_replace(self):
@@ -751,7 +751,7 @@ class TestFlowMaster:
         s = flow.State()
         fm = flow.FlowMaster(None, s)
         f = tutils.tflow(resp=True)
-        f.request.content = CONTENT_MISSING
+        f.request.content = None
         assert "missing" in fm.replay_request(f)
 
         f.intercepted = True
diff --git a/test/mitmproxy/test_flow_export.py b/test/mitmproxy/test_flow_export.py
index ae5536853..d4b255439 100644
--- a/test/mitmproxy/test_flow_export.py
+++ b/test/mitmproxy/test_flow_export.py
@@ -1,3 +1,4 @@
+import json
 from textwrap import dedent
 
 import netlib.tutils
@@ -178,6 +179,7 @@ class TestRawRequest():
         """).strip()
         assert flow_export.raw_request(flow) == result
 
+
 class TestExportLocustCode():
 
     def test_get(self):
@@ -369,3 +371,24 @@ class TestExportLocustTask():
         """.strip() + '\n'
 
         assert flow_export.locust_task(flow) == result
+
+
+class TestIsJson():
+
+    def test_empty(self):
+        assert flow_export.is_json(None, None) == False
+
+    def test_json_type(self):
+        headers = Headers(content_type="application/json")
+        assert flow_export.is_json(headers, "foobar") == False
+
+    def test_valid(self):
+        headers = Headers(content_type="application/foobar")
+        j = flow_export.is_json(headers, '{"name": "example", "email": "example@example.com"}')
+        assert j == False
+
+    def test_valid(self):
+        headers = Headers(content_type="application/json")
+        j = flow_export.is_json(headers, '{"name": "example", "email": "example@example.com"}')
+        assert isinstance(j, dict)
+
diff --git a/test/mitmproxy/test_server.py b/test/mitmproxy/test_server.py
index 26e53e8ae..dc72f032b 100644
--- a/test/mitmproxy/test_server.py
+++ b/test/mitmproxy/test_server.py
@@ -8,7 +8,7 @@ from netlib.tcp import Address
 import netlib.tutils
 from netlib import tcp, http, socks
 from netlib.certutils import SSLCert
-from netlib.http import authentication, CONTENT_MISSING, http1
+from netlib.http import authentication, http1
 from netlib.tutils import raises
 from pathod import pathoc, pathod
 
@@ -281,7 +281,7 @@ class TestHTTP(tservers.HTTPProxyTest, CommonMixin, AppMixin):
 
         self.pathod("200:b@3k")
         assert self.master.state.view[-1].response.stream
-        assert self.master.state.view[-1].response.content == CONTENT_MISSING
+        assert self.master.state.view[-1].response.content is None
         self.master.set_stream_large_bodies(None)
 
     def test_stream_modify(self):
@@ -816,7 +816,7 @@ class MasterIncomplete(tservers.TestMaster):
 
     def handle_request(self, f):
         resp = HTTPResponse.wrap(netlib.tutils.tresp())
-        resp.content = CONTENT_MISSING
+        resp.content = None
         f.reply(resp)
 
 
diff --git a/test/netlib/http/http1/test_assemble.py b/test/netlib/http/http1/test_assemble.py
index 31a62438e..8dcbae8ee 100644
--- a/test/netlib/http/http1/test_assemble.py
+++ b/test/netlib/http/http1/test_assemble.py
@@ -1,6 +1,6 @@
 from __future__ import absolute_import, print_function, division
 from netlib.exceptions import HttpException
-from netlib.http import CONTENT_MISSING, Headers
+from netlib.http import Headers
 from netlib.http.http1.assemble import (
     assemble_request, assemble_request_head, assemble_response,
     assemble_response_head, _assemble_request_line, _assemble_request_headers,
@@ -20,7 +20,7 @@ def test_assemble_request():
     )
 
     with raises(HttpException):
-        assemble_request(treq(content=CONTENT_MISSING))
+        assemble_request(treq(content=None))
 
 
 def test_assemble_request_head():
@@ -41,7 +41,7 @@ def test_assemble_response():
     )
 
     with raises(HttpException):
-        assemble_response(tresp(content=CONTENT_MISSING))
+        assemble_response(tresp(content=None))
 
 
 def test_assemble_response_head():