diff --git a/mitmproxy/tnetstring.py b/mitmproxy/contrib/tnetstring.py
similarity index 100%
rename from mitmproxy/tnetstring.py
rename to mitmproxy/contrib/tnetstring.py
diff --git a/mitmproxy/flow/io.py b/mitmproxy/flow/io.py
index cd3d99869..671ddf437 100644
--- a/mitmproxy/flow/io.py
+++ b/mitmproxy/flow/io.py
@@ -4,7 +4,7 @@ import os
 
 from mitmproxy import exceptions
 from mitmproxy import models
-from mitmproxy import tnetstring
+from mitmproxy.contrib import tnetstring
 from mitmproxy.flow import io_compat
 
 
diff --git a/test/mitmproxy/test_tnetstring.py b/test/mitmproxy/test_contrib_tnetstring.py
similarity index 99%
rename from test/mitmproxy/test_tnetstring.py
rename to test/mitmproxy/test_contrib_tnetstring.py
index 0b16437be..17654ad9a 100644
--- a/test/mitmproxy/test_tnetstring.py
+++ b/test/mitmproxy/test_contrib_tnetstring.py
@@ -4,7 +4,7 @@ import math
 import io
 import struct
 
-from mitmproxy import tnetstring
+from mitmproxy.contrib import tnetstring
 
 MAXINT = 2 ** (struct.Struct('i').size * 8 - 1) - 1
 
diff --git a/test/mitmproxy/test_flow.py b/test/mitmproxy/test_flow.py
index af8256c44..9eaab9aaa 100644
--- a/test/mitmproxy/test_flow.py
+++ b/test/mitmproxy/test_flow.py
@@ -5,7 +5,8 @@ import mock
 
 import netlib.utils
 from netlib.http import Headers
-from mitmproxy import filt, controller, tnetstring, flow
+from mitmproxy import filt, controller, flow
+from mitmproxy.contrib import tnetstring
 from mitmproxy.exceptions import FlowReadException, ScriptException
 from mitmproxy.models import Error
 from mitmproxy.models import Flow