diff --git a/hyper/http20/connection.py b/hyper/http20/connection.py
index b8be292b..816c20ac 100644
--- a/hyper/http20/connection.py
+++ b/hyper/http20/connection.py
@@ -102,7 +102,7 @@ class HTTP20Connection(object):
     def __init__(self, host, port=None, secure=None, window_manager=None,
                  enable_push=False, ssl_context=None, proxy_host=None,
                  proxy_port=None, force_proto=None, proxy_headers=None,
-                 timeout=None, **kwargs):
+                 timeout=None, external_socket=None, **kwargs):
         """
         Creates an HTTP/2 connection to a specific server.
         """
@@ -154,6 +154,8 @@ def __init__(self, host, port=None, secure=None, window_manager=None,
         # timeout
         self._timeout = timeout
 
+        self._sock = external_socket
+
         return
 
     def __init_state(self):