diff --git a/setup.py b/setup.py
index b0ca181..364a84a 100644
--- a/setup.py
+++ b/setup.py
@@ -21,10 +21,8 @@ setup(name="magic-wormhole",
       entry_points={"console_scripts":
                     ["wormhole = wormhole.scripts.runner:entry"]},
       install_requires=["spake2==0.3", "pynacl", "requests", "argparse",
-                        "six"],
+                        "six", "twisted >= 16.1.0"],
       extras_require={"tor": ["txtorcon", "ipaddr"]},
-      # for Twisted support, we want Twisted>=15.5.0. Older Twisteds don't
-      # provide sufficient python3 compatibility.
       test_suite="wormhole.test",
       cmdclass=commands,
       )
diff --git a/src/wormhole/blocking/transit.py b/src/wormhole/blocking/transit.py
deleted file mode 100644
index c520437..0000000
--- a/src/wormhole/blocking/transit.py
+++ /dev/null
@@ -1,400 +0,0 @@
-from __future__ import print_function
-import time, threading, socket
-from six.moves import socketserver
-from binascii import hexlify, unhexlify
-from nacl.secret import SecretBox
-from ..util import ipaddrs
-from ..util.hkdf import HKDF
-from ..errors import UsageError
-from ..timing import DebugTiming
-from ..transit_common import (TransitError, BadHandshake, TransitClosed,
-                              BadNonce,
-                              build_receiver_handshake,
-                              build_sender_handshake,
-                              build_relay_handshake,
-                              parse_hint_tcp)
-
-TIMEOUT=15
-
-# 1: sender only transmits, receiver only accepts, both wait forever
-# 2: sender also accepts, receiver also transmits
-# 3: timeouts / stop when no more progress can be made
-# 4: add relay
-# 5: accelerate shutdown of losing sockets
-
-def send_to(skt, data):
-    sent = 0
-    while sent < len(data):
-        sent += skt.send(data[sent:])
-
-def wait_for_line(skt, max_length, description):
-    got = b""
-    while len(got) < max_length:
-        got += skt.recv(1)
-        if got.endswith(b"\n"):
-            return got[:-1]
-    raise BadHandshake("exceeded max_length, got %r on %s" %
-                       (got, description))
-
-def wait_for(skt, expected, description):
-    assert isinstance(expected, type(b""))
-    got = b""
-    while len(got) < len(expected):
-        got += skt.recv(1)
-        if expected[:len(got)] != got:
-            raise BadHandshake("got %r want %r on %s" %
-                               (got, expected, description))
-
-def debug(msg):
-    if False:
-        print(msg)
-def since(start):
-    return time.time() - start
-
-def connector(owner, hint, description,
-              send_handshake, expected_handshake, relay_handshake=None):
-    start = time.time()
-    parsed_hint = parse_hint_tcp(hint)
-    if not parsed_hint:
-        return # unparseable
-    addr,port = parsed_hint
-    skt = None
-    debug("+ connector(%s)" % hint)
-    try:
-        skt = socket.create_connection((addr,port),
-                                       TIMEOUT) # timeout or ECONNREFUSED
-        skt.settimeout(TIMEOUT)
-        debug(" - socket(%s) connected CT+%.1f" % (description, since(start)))
-        if relay_handshake:
-            debug(" - sending relay_handshake")
-            send_to(skt, relay_handshake)
-            relay_msg = wait_for_line(skt, 10000, description)
-            if relay_msg != b"ok":
-                raise BadHandshake(relay_msg)
-            debug(" - relay ready CT+%.1f" % (since(start),))
-        send_to(skt, send_handshake)
-        wait_for(skt, expected_handshake, description)
-        debug(" + connector(%s) ready CT+%.1f" % (hint, since(start)))
-    except Exception as e:
-        debug(" - error(%s)(%r) CT+%.1f" % (hint, e, since(start)))
-        try:
-            if skt:
-                skt.shutdown(socket.SHUT_WR)
-        except socket.error:
-            pass
-        if skt:
-            skt.close()
-        # ignore socket errors, warn about coding errors
-        if not isinstance(e, (socket.error, socket.timeout, BadHandshake)):
-            raise
-        debug(" - notifying owner._connector_failed(%s) CT+%.1f" % (hint, since(start)))
-        owner._connector_failed(hint)
-        return
-    # owner is now responsible for the socket
-    owner._negotiation_finished(skt, description) # note thread
-
-def handle(skt, client_address, owner, description,
-           send_handshake, expected_handshake):
-    try:
-        debug("handle %r" %  (skt,))
-        skt.settimeout(TIMEOUT)
-        send_to(skt, send_handshake)
-        got = b""
-        # for the receiver, this includes the "go\n"
-        while len(got) < len(expected_handshake):
-            more = skt.recv(1)
-            if not more:
-                raise BadHandshake("disconnect after merely '%r'" % got)
-            got += more
-            if expected_handshake[:len(got)] != got:
-                raise BadHandshake("got '%r' want '%r'" %
-                                   (got, expected_handshake))
-        debug("handler negotiation finished %r" % (client_address,))
-    except Exception as e:
-        debug("handler failed %r" % (client_address,))
-        try:
-            # this raises socket.err(EBADF) if the socket was already closed
-            skt.shutdown(socket.SHUT_WR)
-        except socket.error:
-            pass
-        skt.close() # this appears to be idempotent
-        # ignore socket errors, warn about coding errors
-        if not isinstance(e, (socket.error, socket.timeout, BadHandshake)):
-            raise
-        return
-    # owner is now responsible for the socket
-    owner._negotiation_finished(skt, description) # note thread
-
-class MyTCPServer(socketserver.TCPServer):
-    allow_reuse_address = True
-
-    def process_request(self, request, client_address):
-        description = "<-tcp:%s:%d" % (client_address[0], client_address[1])
-        ready_lock = self.owner._ready_for_connections_lock
-        ready_lock.acquire()
-        while not (self.owner._ready_for_connections
-                   and self.owner._transit_key):
-            ready_lock.wait()
-        # owner._transit_key is either None or set to a value. We don't
-        # modify it from here, so we can release the condition lock before
-        # grabbing the key.
-        ready_lock.release()
-
-        # Once it is set, we can get handler_(send|receive)_handshake, which
-        # is what we actually care about.
-        t = threading.Thread(target=handle,
-                             args=(request, client_address,
-                                   self.owner, description,
-                                   self.owner.handler_send_handshake,
-                                   self.owner.handler_expected_handshake))
-        t.daemon = True
-        t.start()
-
-
-class ReceiveBuffer:
-    def __init__(self, skt):
-        self.skt = skt
-        self.buf = b""
-
-    def read(self, count):
-        while len(self.buf) < count:
-            more = self.skt.recv(4096)
-            if not more:
-                raise TransitClosed
-            self.buf += more
-        rc = self.buf[:count]
-        self.buf = self.buf[count:]
-        return rc
-
-class RecordPipe:
-    def __init__(self, skt, send_key, receive_key, description):
-        self.skt = skt
-        self.send_box = SecretBox(send_key)
-        self.send_nonce = 0
-        self.receive_buf = ReceiveBuffer(self.skt)
-        self.receive_box = SecretBox(receive_key)
-        self.next_receive_nonce = 0
-        self._description = description
-
-    def describe(self):
-        return self._description
-
-    def send_record(self, record):
-        if not isinstance(record, type(b"")): raise UsageError
-        assert SecretBox.NONCE_SIZE == 24
-        assert self.send_nonce < 2**(8*24)
-        assert len(record) < 2**(8*4)
-        nonce = unhexlify("%048x" % self.send_nonce) # big-endian
-        self.send_nonce += 1
-        encrypted = self.send_box.encrypt(record, nonce)
-        length = unhexlify("%08x" % len(encrypted)) # always 4 bytes long
-        send_to(self.skt, length)
-        send_to(self.skt, encrypted)
-
-    def receive_record(self):
-        length_buf = self.receive_buf.read(4)
-        length = int(hexlify(length_buf), 16)
-        encrypted = self.receive_buf.read(length)
-        nonce_buf = encrypted[:SecretBox.NONCE_SIZE] # assume it's prepended
-        nonce = int(hexlify(nonce_buf), 16)
-        if nonce != self.next_receive_nonce:
-            raise BadNonce("received out-of-order record")
-        self.next_receive_nonce += 1
-        record = self.receive_box.decrypt(encrypted)
-        return record
-
-    def close(self):
-        self.skt.close()
-
-class Common:
-    def __init__(self, transit_relay, no_listen=False, timing=None):
-        if transit_relay:
-            if not isinstance(transit_relay, type(u"")):
-                raise UsageError
-            self._transit_relays = [transit_relay]
-        else:
-            self._transit_relays = []
-        self._no_listen = no_listen
-        self._timing = timing or DebugTiming()
-        self._timing_started = self._timing.add_event("transit")
-        self.winning = threading.Event()
-        self._negotiation_check_lock = threading.Lock()
-        self._ready_for_connections_lock = threading.Condition()
-        self._ready_for_connections = False
-        self._transit_key = None
-        self._start_server()
-
-    def _start_server(self):
-        if self._no_listen:
-            self.my_direct_hints = []
-            self.listener = None
-            return
-        server = MyTCPServer(("", 0), None)
-        _, port = server.server_address
-        self.my_direct_hints = [u"tcp:%s:%d" % (addr, port)
-                                for addr in ipaddrs.find_addresses()]
-        server.owner = self
-        server_thread = threading.Thread(target=server.serve_forever)
-        server_thread.daemon = True
-        server_thread.start()
-        self.listener = server
-
-    def get_direct_hints(self):
-        return self.my_direct_hints
-    def get_relay_hints(self):
-        return self._transit_relays
-
-    def add_their_direct_hints(self, hints):
-        for h in hints:
-            if not isinstance(h, type(u"")):
-                raise TypeError("hint '%r' should be unicode, not %s"
-                                % (h, type(h)))
-        self._their_direct_hints = list(hints)
-    def add_their_relay_hints(self, hints):
-        for h in hints:
-            if not isinstance(h, type(u"")):
-                raise TypeError("hint '%r' should be unicode, not %s"
-                                % (h, type(h)))
-        self._their_relay_hints = list(hints)
-
-    def _send_this(self):
-        if self.is_sender:
-            return build_sender_handshake(self._transit_key)
-        else:
-            return build_receiver_handshake(self._transit_key)
-
-    def _expect_this(self):
-        if self.is_sender:
-            return build_receiver_handshake(self._transit_key)
-        else:
-            return build_sender_handshake(self._transit_key) + b"go\n"
-
-    def _sender_record_key(self):
-        if self.is_sender:
-            return HKDF(self._transit_key, SecretBox.KEY_SIZE,
-                        CTXinfo=b"transit_record_sender_key")
-        else:
-            return HKDF(self._transit_key, SecretBox.KEY_SIZE,
-                        CTXinfo=b"transit_record_receiver_key")
-
-    def _receiver_record_key(self):
-        if self.is_sender:
-            return HKDF(self._transit_key, SecretBox.KEY_SIZE,
-                        CTXinfo=b"transit_record_receiver_key")
-        else:
-            return HKDF(self._transit_key, SecretBox.KEY_SIZE,
-                        CTXinfo=b"transit_record_sender_key")
-
-    def set_transit_key(self, key):
-        # This _ready_for_connections condition/lock protects us against the
-        # race where the sender knows the hints and the key, and connects to
-        # the receiver's transit socket before the receiver gets relay
-        # message (and thus the key).
-        self._ready_for_connections_lock.acquire()
-        self._transit_key = key
-        self.handler_send_handshake = self._send_this() # no "go"
-        self.handler_expected_handshake = self._expect_this()
-        self._ready_for_connections_lock.notify_all()
-        self._ready_for_connections_lock.release()
-
-    def _start_outbound(self):
-        self._active_connectors = set(self._their_direct_hints)
-        self._attempted_connectors = set()
-        for hint in self._their_direct_hints:
-            self._start_connector(hint)
-        if not self._their_direct_hints:
-            self._start_relay_connectors()
-
-    def _start_connector(self, hint, is_relay=False):
-        # Don't try any hint more than once. If all hints fail, we'll
-        # eventually timeout. We make no attempt to fail any faster.
-        if hint in self._attempted_connectors:
-            return
-        self._attempted_connectors.add(hint)
-        description = "->%s" % (hint,)
-        if is_relay:
-            description = "->relay:%s" % (hint,)
-        args = (self, hint, description,
-                self._send_this(), self._expect_this())
-        if is_relay:
-            args = args + (build_relay_handshake(self._transit_key),)
-        t = threading.Thread(target=connector, args=args)
-        t.daemon = True
-        t.start()
-
-    def _start_relay_connectors(self):
-        self._active_connectors.update(self._their_direct_hints)
-        for hint in self._their_relay_hints:
-            self._start_connector(hint, is_relay=True)
-
-    def establish_socket(self):
-        start = time.time()
-        self.winning_skt = None
-        self.winning_skt_description = None
-        self._ready_for_connections_lock.acquire()
-        self._ready_for_connections = True
-        self._ready_for_connections_lock.notify_all()
-        self._ready_for_connections_lock.release()
-        self._start_outbound()
-
-        # we sit here until one of our inbound or outbound sockets succeeds
-        flag = self.winning.wait(2*TIMEOUT)
-        debug("wait returned at %.1f" % (since(start),))
-
-        if not flag:
-            # timeout: self.winning_skt will not be set. ish. race.
-            pass
-        if self.listener:
-            self.listener.shutdown() # TODO: waits up to 0.5s. push to thread
-        if self.winning_skt:
-            return self.winning_skt
-        raise TransitError("timeout")
-
-    def _connector_failed(self, hint):
-        debug("- failed connector %s" % hint)
-        # XXX this was .remove, and occasionally got KeyError
-        self._active_connectors.discard(hint)
-        if not self._active_connectors:
-            self._start_relay_connectors()
-
-    def _negotiation_finished(self, skt, description):
-        # inbound/outbound sockets call this when they finish negotiation.
-        # The first one wins and gets a "go". Any subsequent ones lose and
-        # get a "nevermind" before being closed.
-
-        with self._negotiation_check_lock:
-            if self.winning_skt:
-                is_winner = False
-            else:
-                is_winner = True
-                self.winning_skt = skt
-                self.winning_skt_description = description
-
-        if is_winner:
-            if self.is_sender:
-                send_to(skt, b"go\n")
-            self.winning.set()
-        else:
-            if self.is_sender:
-                try:
-                    send_to(skt, b"nevermind\n")
-                except socket.error:
-                    # They realized this connection is not going to win, and
-                    # closed it so fast we didn't get a chance to tell them
-                    # it lost. This happens in unit tests.
-                    pass
-            skt.close()
-
-    def connect(self):
-        _start = self._timing.add_event("transit connect")
-        skt = self.establish_socket()
-        self._timing.finish_event(_start)
-        return RecordPipe(skt, self._sender_record_key(),
-                          self._receiver_record_key(),
-                          self.winning_skt_description)
-
-class TransitSender(Common):
-    is_sender = True
-
-class TransitReceiver(Common):
-    is_sender = False
diff --git a/src/wormhole/scripts/cli_args.py b/src/wormhole/scripts/cli_args.py
index 90169d4..c650768 100644
--- a/src/wormhole/scripts/cli_args.py
+++ b/src/wormhole/scripts/cli_args.py
@@ -27,8 +27,6 @@ g.add_argument("--hide-progress", action="store_true",
                help="supress progress-bar display")
 g.add_argument("--dump-timing", type=type(u""), # TODO: hide from --help output
                metavar="FILE", help="(debug) write timing data to file")
-g.add_argument("--twisted", action="store_true",
-               help="use Twisted-based implementations, for testing")
 g.add_argument("--no-listen", action="store_true",
                help="(debug) don't open a listening socket for Transit")
 g.add_argument("--tor", action="store_true",
diff --git a/src/wormhole/scripts/cmd_receive_twisted.py b/src/wormhole/scripts/cmd_receive.py
similarity index 62%
rename from src/wormhole/scripts/cmd_receive_twisted.py
rename to src/wormhole/scripts/cmd_receive.py
index fb7dd3d..a48ade7 100644
--- a/src/wormhole/scripts/cmd_receive_twisted.py
+++ b/src/wormhole/scripts/cmd_receive.py
@@ -1,13 +1,19 @@
 from __future__ import print_function
-import io, json
+import io, os, sys, json, binascii, six, tempfile, zipfile
 from twisted.internet import reactor, defer
 from twisted.internet.defer import inlineCallbacks, returnValue
 from ..twisted.transcribe import Wormhole, WrongPasswordError
 from ..twisted.transit import TransitReceiver
-from .cmd_receive_blocking import BlockingReceiver, RespondError, APPID
 from ..errors import TransferError
 from .progress import ProgressPrinter
 
+
+APPID = u"lothar.com/wormhole/text-or-file-xfer"
+
+class RespondError(Exception):
+    def __init__(self, response):
+        self.response = response
+
 def receive_twisted_sync(args):
     # try to use twisted.internet.task.react(f) here (but it calls sys.exit
     # directly)
@@ -34,7 +40,14 @@ def receive_twisted_sync(args):
 def receive_twisted(args):
     return TwistedReceiver(args).go()
 
-class TwistedReceiver(BlockingReceiver):
+
+class TwistedReceiver:
+    def __init__(self, args):
+        assert isinstance(args.relay_url, type(u""))
+        self.args = args
+
+    def msg(self, *args, **kwargs):
+        print(*args, file=self.args.stdout, **kwargs)
 
     # TODO: @handle_server_error
     @inlineCallbacks
@@ -101,6 +114,11 @@ class TwistedReceiver(BlockingReceiver):
                                       self.args.code_length)
         yield w.set_code(code)
 
+    def show_verifier(self, verifier):
+        verifier_hex = binascii.hexlify(verifier).decode("ascii")
+        if self.args.verify:
+            self.msg(u"Verifier %s." % verifier_hex)
+
     @inlineCallbacks
     def get_data(self, w):
         try:
@@ -119,6 +137,61 @@ class TwistedReceiver(BlockingReceiver):
         data = json.dumps({"message_ack": "ok"}).encode("utf-8")
         yield w.send_data(data)
 
+    def handle_file(self, them_d):
+        file_data = them_d["file"]
+        self.abs_destname = self.decide_destname("file",
+                                                 file_data["filename"])
+        self.xfersize = file_data["filesize"]
+
+        self.msg(u"Receiving file (%d bytes) into: %s" %
+                 (self.xfersize, os.path.basename(self.abs_destname)))
+        self.ask_permission()
+        tmp_destname = self.abs_destname + ".tmp"
+        return open(tmp_destname, "wb")
+
+    def handle_directory(self, them_d):
+        file_data = them_d["directory"]
+        zipmode = file_data["mode"]
+        if zipmode != "zipfile/deflated":
+            self.msg(u"Error: unknown directory-transfer mode '%s'" % (zipmode,))
+            raise RespondError({"error": "unknown mode"})
+        self.abs_destname = self.decide_destname("directory",
+                                                 file_data["dirname"])
+        self.xfersize = file_data["zipsize"]
+
+        self.msg(u"Receiving directory (%d bytes) into: %s/" %
+                 (self.xfersize, os.path.basename(self.abs_destname)))
+        self.msg(u"%d files, %d bytes (uncompressed)" %
+                 (file_data["numfiles"], file_data["numbytes"]))
+        self.ask_permission()
+        return tempfile.SpooledTemporaryFile()
+
+    def decide_destname(self, mode, destname):
+        # the basename() is intended to protect us against
+        # "~/.ssh/authorized_keys" and other attacks
+        destname = os.path.basename(destname)
+        if self.args.output_file:
+            destname = self.args.output_file # override
+        abs_destname = os.path.join(self.args.cwd, destname)
+
+        # get confirmation from the user before writing to the local directory
+        if os.path.exists(abs_destname):
+            self.msg(u"Error: refusing to overwrite existing %s %s" %
+                     (mode, destname))
+            raise RespondError({"error": "%s already exists" % mode})
+        return abs_destname
+
+    def ask_permission(self):
+        _start = self.args.timing.add_event("permission", waiting="user")
+        while True and not self.args.accept_file:
+            ok = six.moves.input("ok? (y/n): ")
+            if ok.lower().startswith("y"):
+                break
+            print(u"transfer rejected", file=sys.stderr)
+            self.args.timing.finish_event(_start, answer="no")
+            raise RespondError({"error": "transfer rejected"})
+        self.args.timing.finish_event(_start, answer="yes")
+
     @inlineCallbacks
     def establish_transit(self, w, them_d, tor_manager):
         transit_key = w.derive_key(APPID+u"/transit-key")
@@ -169,6 +242,27 @@ class TwistedReceiver(BlockingReceiver):
             returnValue(1) # TODO: exit properly
         assert received == self.xfersize
 
+    def write_file(self, f):
+        tmp_name = f.name
+        f.close()
+        os.rename(tmp_name, self.abs_destname)
+        self.msg(u"Received file written to %s" %
+                 os.path.basename(self.abs_destname))
+
+    def write_directory(self, f):
+        self.msg(u"Unpacking zipfile..")
+        _start = self.args.timing.add_event("unpack zip")
+        with zipfile.ZipFile(f, "r", zipfile.ZIP_DEFLATED) as zf:
+            zf.extractall(path=self.abs_destname)
+            # extractall() appears to offer some protection against
+            # malicious pathnames. For example, "/tmp/oops" and
+            # "../tmp/oops" both do the same thing as the (safe)
+            # "tmp/oops".
+        self.msg(u"Received files written to %s/" %
+                 os.path.basename(self.abs_destname))
+        f.close()
+        self.args.timing.finish_event(_start)
+
     @inlineCallbacks
     def close_transit(self, record_pipe):
         _start = self.args.timing.add_event("ack")
diff --git a/src/wormhole/scripts/cmd_receive_blocking.py b/src/wormhole/scripts/cmd_receive_blocking.py
deleted file mode 100644
index afecd06..0000000
--- a/src/wormhole/scripts/cmd_receive_blocking.py
+++ /dev/null
@@ -1,216 +0,0 @@
-from __future__ import print_function
-import io, os, sys, json, binascii, six, tempfile, zipfile
-from ..blocking.transcribe import Wormhole, WrongPasswordError
-from ..blocking.transit import TransitReceiver, TransitError
-from ..errors import handle_server_error, TransferError
-from .progress import ProgressPrinter
-
-APPID = u"lothar.com/wormhole/text-or-file-xfer"
-
-def receive_blocking(args):
-    return BlockingReceiver(args).go()
-
-class RespondError(Exception):
-    def __init__(self, response):
-        self.response = response
-
-class BlockingReceiver:
-    def __init__(self, args):
-        assert isinstance(args.relay_url, type(u""))
-        self.args = args
-
-    def msg(self, *args, **kwargs):
-        print(*args, file=self.args.stdout, **kwargs)
-
-    @handle_server_error
-    def go(self):
-        with Wormhole(APPID, self.args.relay_url, timing=self.args.timing) as w:
-            self.handle_code(w)
-            verifier = w.get_verifier()
-            self.show_verifier(verifier)
-            them_d = self.get_data(w)
-            try:
-                if "message" in them_d:
-                    self.handle_text(them_d, w)
-                    return 0
-                if "file" in them_d:
-                    f = self.handle_file(them_d)
-                    rp = self.establish_transit(w, them_d)
-                    self.transfer_data(rp, f)
-                    self.write_file(f)
-                    self.close_transit(rp)
-                elif "directory" in them_d:
-                    f = self.handle_directory(them_d)
-                    rp = self.establish_transit(w, them_d)
-                    self.transfer_data(rp, f)
-                    self.write_directory(f)
-                    self.close_transit(rp)
-                else:
-                    self.msg(u"I don't know what they're offering\n")
-                    self.msg(u"Offer details:", them_d)
-                    raise RespondError({"error": "unknown offer type"})
-            except RespondError as r:
-                data = json.dumps(r.response).encode("utf-8")
-                w.send_data(data)
-                return 1
-            return 0
-
-    def handle_code(self, w):
-        code = self.args.code
-        if self.args.zeromode:
-            assert not code
-            code = u"0-"
-        if not code:
-            code = w.input_code("Enter receive wormhole code: ",
-                                self.args.code_length)
-        w.set_code(code)
-
-    def show_verifier(self, verifier):
-        verifier_hex = binascii.hexlify(verifier).decode("ascii")
-        if self.args.verify:
-            self.msg(u"Verifier %s." % verifier_hex)
-
-    def get_data(self, w):
-        try:
-            them_bytes = w.get_data()
-        except WrongPasswordError as e:
-            raise TransferError(u"ERROR: " + e.explain())
-        them_d = json.loads(them_bytes.decode("utf-8"))
-        if "error" in them_d:
-            raise TransferError(u"ERROR: " + them_d["error"])
-        return them_d
-
-    def handle_text(self, them_d, w):
-        # we're receiving a text message
-        self.msg(them_d["message"])
-        data = json.dumps({"message_ack": "ok"}).encode("utf-8")
-        w.send_data(data)
-
-    def handle_file(self, them_d):
-        file_data = them_d["file"]
-        self.abs_destname = self.decide_destname("file",
-                                                 file_data["filename"])
-        self.xfersize = file_data["filesize"]
-
-        self.msg(u"Receiving file (%d bytes) into: %s" %
-                 (self.xfersize, os.path.basename(self.abs_destname)))
-        self.ask_permission()
-        tmp_destname = self.abs_destname + ".tmp"
-        return open(tmp_destname, "wb")
-
-    def handle_directory(self, them_d):
-        file_data = them_d["directory"]
-        zipmode = file_data["mode"]
-        if zipmode != "zipfile/deflated":
-            self.msg(u"Error: unknown directory-transfer mode '%s'" % (zipmode,))
-            raise RespondError({"error": "unknown mode"})
-        self.abs_destname = self.decide_destname("directory",
-                                                 file_data["dirname"])
-        self.xfersize = file_data["zipsize"]
-
-        self.msg(u"Receiving directory (%d bytes) into: %s/" %
-                 (self.xfersize, os.path.basename(self.abs_destname)))
-        self.msg(u"%d files, %d bytes (uncompressed)" %
-                 (file_data["numfiles"], file_data["numbytes"]))
-        self.ask_permission()
-        return tempfile.SpooledTemporaryFile()
-
-    def decide_destname(self, mode, destname):
-        # the basename() is intended to protect us against
-        # "~/.ssh/authorized_keys" and other attacks
-        destname = os.path.basename(destname)
-        if self.args.output_file:
-            destname = self.args.output_file # override
-        abs_destname = os.path.join(self.args.cwd, destname)
-
-        # get confirmation from the user before writing to the local directory
-        if os.path.exists(abs_destname):
-            self.msg(u"Error: refusing to overwrite existing %s %s" %
-                     (mode, destname))
-            raise RespondError({"error": "%s already exists" % mode})
-        return abs_destname
-
-    def ask_permission(self):
-        _start = self.args.timing.add_event("permission", waiting="user")
-        while True and not self.args.accept_file:
-            ok = six.moves.input("ok? (y/n): ")
-            if ok.lower().startswith("y"):
-                break
-            print(u"transfer rejected", file=sys.stderr)
-            self.args.timing.finish_event(_start, answer="no")
-            raise RespondError({"error": "transfer rejected"})
-        self.args.timing.finish_event(_start, answer="yes")
-
-    def establish_transit(self, w, them_d):
-        transit_key = w.derive_key(APPID+u"/transit-key")
-        transit_receiver = TransitReceiver(self.args.transit_helper,
-                                           no_listen=self.args.no_listen,
-                                           timing=self.args.timing)
-        transit_receiver.set_transit_key(transit_key)
-        data = json.dumps({
-            "file_ack": "ok",
-            "transit": {
-                "direct_connection_hints": transit_receiver.get_direct_hints(),
-                "relay_connection_hints": transit_receiver.get_relay_hints(),
-                },
-            }).encode("utf-8")
-        w.send_data(data)
-
-        # now receive the rest of the owl
-        tdata = them_d["transit"]
-        transit_receiver.add_their_direct_hints(tdata["direct_connection_hints"])
-        transit_receiver.add_their_relay_hints(tdata["relay_connection_hints"])
-        record_pipe = transit_receiver.connect()
-        return record_pipe
-
-    def transfer_data(self, record_pipe, f):
-        self.msg(u"Receiving (%s).." % record_pipe.describe())
-
-        _start = self.args.timing.add_event("rx file")
-        progress_stdout = self.args.stdout
-        if self.args.hide_progress:
-            progress_stdout = io.StringIO()
-        received = 0
-        p = ProgressPrinter(self.xfersize, progress_stdout)
-        p.start()
-        while received < self.xfersize:
-            try:
-                plaintext = record_pipe.receive_record()
-            except TransitError:
-                self.msg()
-                self.msg(u"Connection dropped before full file received")
-                self.msg(u"got %d bytes, wanted %d" % (received, self.xfersize))
-                return 1
-            f.write(plaintext)
-            received += len(plaintext)
-            p.update(received)
-        p.finish()
-        self.args.timing.finish_event(_start)
-        assert received == self.xfersize
-
-    def write_file(self, f):
-        tmp_name = f.name
-        f.close()
-        os.rename(tmp_name, self.abs_destname)
-        self.msg(u"Received file written to %s" %
-                 os.path.basename(self.abs_destname))
-
-    def write_directory(self, f):
-        self.msg(u"Unpacking zipfile..")
-        _start = self.args.timing.add_event("unpack zip")
-        with zipfile.ZipFile(f, "r", zipfile.ZIP_DEFLATED) as zf:
-            zf.extractall(path=self.abs_destname)
-            # extractall() appears to offer some protection against
-            # malicious pathnames. For example, "/tmp/oops" and
-            # "../tmp/oops" both do the same thing as the (safe)
-            # "tmp/oops".
-        self.msg(u"Received files written to %s/" %
-                 os.path.basename(self.abs_destname))
-        f.close()
-        self.args.timing.finish_event(_start)
-
-    def close_transit(self, record_pipe):
-        _start = self.args.timing.add_event("ack")
-        record_pipe.send_record(b"ok\n")
-        record_pipe.close()
-        self.args.timing.finish_event(_start)
diff --git a/src/wormhole/scripts/cmd_send_twisted.py b/src/wormhole/scripts/cmd_send.py
similarity index 67%
rename from src/wormhole/scripts/cmd_send_twisted.py
rename to src/wormhole/scripts/cmd_send.py
index 092c8cb..442a591 100644
--- a/src/wormhole/scripts/cmd_send_twisted.py
+++ b/src/wormhole/scripts/cmd_send.py
@@ -1,5 +1,5 @@
 from __future__ import print_function
-import io, json, binascii, six
+import os, sys, io, json, binascii, six, tempfile, zipfile
 from twisted.protocols import basic
 from twisted.internet import reactor, defer
 from twisted.internet.defer import inlineCallbacks, returnValue
@@ -7,8 +7,94 @@ from ..errors import TransferError
 from .progress import ProgressPrinter
 from ..twisted.transcribe import Wormhole, WrongPasswordError
 from ..twisted.transit import TransitSender
-from .send_common import (APPID, handle_zero, build_other_command,
-                          build_phase1_data)
+
+APPID = u"lothar.com/wormhole/text-or-file-xfer"
+
+def handle_zero(args):
+    if args.zeromode:
+        assert not args.code
+        args.code = u"0-"
+
+def build_other_command(args):
+    other_cmd = "wormhole receive"
+    if args.verify:
+        other_cmd = "wormhole --verify receive"
+    if args.zeromode:
+        other_cmd += " -0"
+    return other_cmd
+
+def build_phase1_data(args):
+    phase1 = {}
+
+    text = args.text
+    if text == "-":
+        print(u"Reading text message from stdin..", file=args.stdout)
+        text = sys.stdin.read()
+    if not text and not args.what:
+        text = six.moves.input("Text to send: ")
+
+    if text is not None:
+        print(u"Sending text message (%d bytes)" % len(text), file=args.stdout)
+        phase1 = { "message": text }
+        fd_to_send = None
+        return phase1, fd_to_send
+
+    what = os.path.join(args.cwd, args.what)
+    what = what.rstrip(os.sep)
+    if not os.path.exists(what):
+        raise TransferError("Cannot send: no file/directory named '%s'" %
+                            args.what)
+    basename = os.path.basename(what)
+
+    if os.path.isfile(what):
+        # we're sending a file
+        filesize = os.stat(what).st_size
+        phase1["file"] = {
+            "filename": basename,
+            "filesize": filesize,
+            }
+        print(u"Sending %d byte file named '%s'" % (filesize, basename),
+              file=args.stdout)
+        fd_to_send = open(what, "rb")
+        return phase1, fd_to_send
+
+    if os.path.isdir(what):
+        print(u"Building zipfile..", file=args.stdout)
+        # We're sending a directory. Create a zipfile in a tempdir and
+        # send that.
+        fd_to_send = tempfile.SpooledTemporaryFile()
+        # TODO: I think ZIP_DEFLATED means compressed.. check it
+        num_files = 0
+        num_bytes = 0
+        tostrip = len(what.split(os.sep))
+        with zipfile.ZipFile(fd_to_send, "w", zipfile.ZIP_DEFLATED) as zf:
+            for path,dirs,files in os.walk(what):
+                # path always starts with args.what, then sometimes might
+                # have "/subdir" appended. We want the zipfile to contain
+                # "" or "subdir"
+                localpath = list(path.split(os.sep)[tostrip:])
+                for fn in files:
+                    archivename = os.path.join(*tuple(localpath+[fn]))
+                    localfilename = os.path.join(path, fn)
+                    zf.write(localfilename, archivename)
+                    num_bytes += os.stat(localfilename).st_size
+                    num_files += 1
+        fd_to_send.seek(0,2)
+        filesize = fd_to_send.tell()
+        fd_to_send.seek(0,0)
+        phase1["directory"] = {
+            "mode": "zipfile/deflated",
+            "dirname": basename,
+            "zipsize": filesize,
+            "numbytes": num_bytes,
+            "numfiles": num_files,
+            }
+        print(u"Sending directory (%d bytes compressed) named '%s'"
+              % (filesize, basename), file=args.stdout)
+        return phase1, fd_to_send
+
+    raise TypeError("'%s' is neither file nor directory" % args.what)
+
 
 def send_twisted_sync(args):
     # try to use twisted.internet.task.react(f) here (but it calls sys.exit
diff --git a/src/wormhole/scripts/cmd_send_blocking.py b/src/wormhole/scripts/cmd_send_blocking.py
deleted file mode 100644
index 7259185..0000000
--- a/src/wormhole/scripts/cmd_send_blocking.py
+++ /dev/null
@@ -1,129 +0,0 @@
-from __future__ import print_function
-import json, binascii, six
-from ..errors import TransferError
-from .progress import ProgressPrinter
-from ..blocking.transcribe import Wormhole, WrongPasswordError
-from ..blocking.transit import TransitSender
-from ..errors import handle_server_error
-from .send_common import (APPID, handle_zero, build_other_command,
-                          build_phase1_data)
-
-@handle_server_error
-def send_blocking(args):
-    assert isinstance(args.relay_url, type(u""))
-    handle_zero(args)
-    phase1, fd_to_send = build_phase1_data(args)
-    other_cmd = build_other_command(args)
-    print(u"On the other computer, please run: %s" % other_cmd,
-          file=args.stdout)
-
-    if fd_to_send is not None:
-        transit_sender = TransitSender(args.transit_helper,
-                                       no_listen=args.no_listen,
-                                       timing=args.timing)
-        transit_data = {
-            "direct_connection_hints": transit_sender.get_direct_hints(),
-            "relay_connection_hints": transit_sender.get_relay_hints(),
-            }
-        phase1["transit"] = transit_data
-
-    with Wormhole(APPID, args.relay_url, timing=args.timing) as w:
-        if args.code:
-            w.set_code(args.code)
-            code = args.code
-        else:
-            code = w.get_code(args.code_length)
-        if not args.zeromode:
-            print(u"Wormhole code is: %s" % code, file=args.stdout)
-        print(u"", file=args.stdout)
-
-        # get the verifier, because that also lets us derive the transit key,
-        # which we want to set before revealing the connection hints to the
-        # far side, so we'll be ready for them when they connect
-        verifier = binascii.hexlify(w.get_verifier()).decode("ascii")
-        if args.verify:
-            _do_verify(verifier, w)
-
-        if fd_to_send is not None:
-            transit_key = w.derive_key(APPID+"/transit-key")
-            transit_sender.set_transit_key(transit_key)
-
-        my_phase1_bytes = json.dumps(phase1).encode("utf-8")
-        w.send_data(my_phase1_bytes)
-        try:
-            them_phase1_bytes = w.get_data()
-        except WrongPasswordError as e:
-            raise TransferError(e.explain())
-
-    them_phase1 = json.loads(them_phase1_bytes.decode("utf-8"))
-
-    if fd_to_send is None:
-        if them_phase1["message_ack"] == "ok":
-            print(u"text message sent", file=args.stdout)
-            return 0
-        raise TransferError("error sending text: %r" % (them_phase1,))
-
-    return _send_file_blocking(them_phase1, fd_to_send,
-                               transit_sender, args.stdout, args.hide_progress,
-                               args.timing)
-
-def _do_verify(verifier, w):
-    while True:
-        ok = six.moves.input("Verifier %s. ok? (yes/no): " % verifier)
-        if ok.lower() == "yes":
-            break
-        if ok.lower() == "no":
-            reject_data = json.dumps({"error": "verification rejected",
-                                      }).encode("utf-8")
-            w.send_data(reject_data)
-            raise TransferError("verification rejected, abandoning transfer")
-
-def _send_file_blocking(them_phase1, fd_to_send, transit_sender,
-                        stdout, hide_progress, timing):
-
-    # we're sending a file, if they accept it
-
-    if "error" in them_phase1:
-        raise TransferError("remote error, transfer abandoned: %s"
-                            % them_phase1["error"])
-    if them_phase1.get("file_ack") != "ok":
-        raise TransferError("ambiguous response from remote, "
-                            "transfer abandoned: %s" % (them_phase1,))
-
-    tdata = them_phase1["transit"]
-    transit_sender.add_their_direct_hints(tdata["direct_connection_hints"])
-    transit_sender.add_their_relay_hints(tdata["relay_connection_hints"])
-    record_pipe = transit_sender.connect()
-
-    print(u"Sending (%s).." % record_pipe.describe(), file=stdout)
-
-    _start = timing.add_event("tx file")
-    CHUNKSIZE = 64*1024
-    fd_to_send.seek(0,2)
-    filesize = fd_to_send.tell()
-    fd_to_send.seek(0,0)
-    p = ProgressPrinter(filesize, stdout)
-    with fd_to_send as f:
-        sent = 0
-        if not hide_progress:
-            p.start()
-        while sent < filesize:
-            plaintext = f.read(CHUNKSIZE)
-            record_pipe.send_record(plaintext)
-            sent += len(plaintext)
-            if not hide_progress:
-                p.update(sent)
-        if not hide_progress:
-            p.finish()
-    timing.finish_event(_start)
-
-    _start = timing.add_event("get ack")
-    print(u"File sent.. waiting for confirmation", file=stdout)
-    ack = record_pipe.receive_record()
-    record_pipe.close()
-    if ack == b"ok\n":
-        print(u"Confirmation received. Transfer complete.", file=stdout)
-        timing.finish_event(_start, ack="ok")
-        return 0
-    timing.finish_event(_start, ack="failed")
-    raise TransferError("Transfer failed (remote says: %r)" % ack)
diff --git a/src/wormhole/scripts/runner.py b/src/wormhole/scripts/runner.py
index 32e9c88..8cff151 100644
--- a/src/wormhole/scripts/runner.py
+++ b/src/wormhole/scripts/runner.py
@@ -21,22 +21,14 @@ def dispatch(args):
         from ..servers import cmd_usage
         return cmd_usage.tail_usage(args)
 
-    if args.tor:
-        args.twisted = True
     if args.func == "send/send":
-        if args.twisted:
-            from . import cmd_send_twisted
-            return cmd_send_twisted.send_twisted_sync(args)
-        from . import cmd_send_blocking
-        return cmd_send_blocking.send_blocking(args)
+        from . import cmd_send
+        return cmd_send.send_twisted_sync(args)
     if args.func == "receive/receive":
-        if args.twisted:
-            _start = args.timing.add_event("import c_r_t")
-            from . import cmd_receive_twisted
-            args.timing.finish_event(_start)
-            return cmd_receive_twisted.receive_twisted_sync(args)
-        from . import cmd_receive_blocking
-        return cmd_receive_blocking.receive_blocking(args)
+        _start = args.timing.add_event("import c_r_t")
+        from . import cmd_receive
+        args.timing.finish_event(_start)
+        return cmd_receive.receive_twisted_sync(args)
 
     raise ValueError("unknown args.func %s" % args.func)
 
diff --git a/src/wormhole/scripts/send_common.py b/src/wormhole/scripts/send_common.py
deleted file mode 100644
index a8f3080..0000000
--- a/src/wormhole/scripts/send_common.py
+++ /dev/null
@@ -1,90 +0,0 @@
-from __future__ import print_function
-import os, sys, six, tempfile, zipfile
-from ..errors import TransferError
-
-APPID = u"lothar.com/wormhole/text-or-file-xfer"
-
-def handle_zero(args):
-    if args.zeromode:
-        assert not args.code
-        args.code = u"0-"
-
-def build_other_command(args):
-    other_cmd = "wormhole receive"
-    if args.verify:
-        other_cmd = "wormhole --verify receive"
-    if args.zeromode:
-        other_cmd += " -0"
-    return other_cmd
-
-def build_phase1_data(args):
-    phase1 = {}
-
-    text = args.text
-    if text == "-":
-        print(u"Reading text message from stdin..", file=args.stdout)
-        text = sys.stdin.read()
-    if not text and not args.what:
-        text = six.moves.input("Text to send: ")
-
-    if text is not None:
-        print(u"Sending text message (%d bytes)" % len(text), file=args.stdout)
-        phase1 = { "message": text }
-        fd_to_send = None
-        return phase1, fd_to_send
-
-    what = os.path.join(args.cwd, args.what)
-    what = what.rstrip(os.sep)
-    if not os.path.exists(what):
-        raise TransferError("Cannot send: no file/directory named '%s'" %
-                            args.what)
-    basename = os.path.basename(what)
-
-    if os.path.isfile(what):
-        # we're sending a file
-        filesize = os.stat(what).st_size
-        phase1["file"] = {
-            "filename": basename,
-            "filesize": filesize,
-            }
-        print(u"Sending %d byte file named '%s'" % (filesize, basename),
-              file=args.stdout)
-        fd_to_send = open(what, "rb")
-        return phase1, fd_to_send
-
-    if os.path.isdir(what):
-        print(u"Building zipfile..", file=args.stdout)
-        # We're sending a directory. Create a zipfile in a tempdir and
-        # send that.
-        fd_to_send = tempfile.SpooledTemporaryFile()
-        # TODO: I think ZIP_DEFLATED means compressed.. check it
-        num_files = 0
-        num_bytes = 0
-        tostrip = len(what.split(os.sep))
-        with zipfile.ZipFile(fd_to_send, "w", zipfile.ZIP_DEFLATED) as zf:
-            for path,dirs,files in os.walk(what):
-                # path always starts with args.what, then sometimes might
-                # have "/subdir" appended. We want the zipfile to contain
-                # "" or "subdir"
-                localpath = list(path.split(os.sep)[tostrip:])
-                for fn in files:
-                    archivename = os.path.join(*tuple(localpath+[fn]))
-                    localfilename = os.path.join(path, fn)
-                    zf.write(localfilename, archivename)
-                    num_bytes += os.stat(localfilename).st_size
-                    num_files += 1
-        fd_to_send.seek(0,2)
-        filesize = fd_to_send.tell()
-        fd_to_send.seek(0,0)
-        phase1["directory"] = {
-            "mode": "zipfile/deflated",
-            "dirname": basename,
-            "zipsize": filesize,
-            "numbytes": num_bytes,
-            "numfiles": num_files,
-            }
-        print(u"Sending directory (%d bytes compressed) named '%s'"
-              % (filesize, basename), file=args.stdout)
-        return phase1, fd_to_send
-
-    raise TypeError("'%s' is neither file nor directory" % args.what)
diff --git a/src/wormhole/test/common.py b/src/wormhole/test/common.py
index 56aa38e..ee2de77 100644
--- a/src/wormhole/test/common.py
+++ b/src/wormhole/test/common.py
@@ -1,7 +1,7 @@
 from twisted.application import service
 from twisted.internet import reactor, defer
 from twisted.python import log
-from ..twisted.util import allocate_ports
+from ..twisted.transit import allocate_tcp_port
 from ..servers.server import RelayServer
 from .. import __version__
 
@@ -9,19 +9,16 @@ class ServerBase:
     def setUp(self):
         self.sp = service.MultiService()
         self.sp.startService()
-        d = allocate_ports()
-        def _got_ports(ports):
-            relayport, transitport = ports
-            s = RelayServer("tcp:%d:interface=127.0.0.1" % relayport,
-                            "tcp:%s:interface=127.0.0.1" % transitport,
-                            __version__)
-            s.setServiceParent(self.sp)
-            self._relay_server = s.relay
-            self._transit_server = s.transit
-            self.relayurl = u"http://127.0.0.1:%d/wormhole-relay/" % relayport
-            self.transit = u"tcp:127.0.0.1:%d" % transitport
-        d.addCallback(_got_ports)
-        return d
+        relayport = allocate_tcp_port()
+        transitport = allocate_tcp_port()
+        s = RelayServer("tcp:%d:interface=127.0.0.1" % relayport,
+                        "tcp:%s:interface=127.0.0.1" % transitport,
+                        __version__)
+        s.setServiceParent(self.sp)
+        self._relay_server = s.relay
+        self._transit_server = s.transit
+        self.relayurl = u"http://127.0.0.1:%d/wormhole-relay/" % relayport
+        self.transit = u"tcp:127.0.0.1:%d" % transitport
 
     def tearDown(self):
         # Unit tests that spawn a (blocking) client in a thread might still
diff --git a/src/wormhole/test/test_blocking.py b/src/wormhole/test/test_blocking.py
index 1fbfaff..e930604 100644
--- a/src/wormhole/test/test_blocking.py
+++ b/src/wormhole/test/test_blocking.py
@@ -1,14 +1,11 @@
 from __future__ import print_function
 import json
 from twisted.trial import unittest
-from twisted.internet.defer import gatherResults, succeed, inlineCallbacks
+from twisted.internet.defer import gatherResults, succeed
 from twisted.internet.threads import deferToThread
 from ..blocking.transcribe import (Wormhole, UsageError, ChannelManager,
                                    WrongPasswordError)
 from ..blocking.eventsource import EventSourceFollower
-from ..blocking.transit import (TransitSender, TransitReceiver,
-                                build_sender_handshake,
-                                build_receiver_handshake)
 from .common import ServerBase
 
 APPID = u"appid"
@@ -447,101 +444,3 @@ class EventSourceClient(unittest.TestCase):
                               (u"message", u"three"),
                               (u"e2", u"four"),
                               ])
-
-class Transit(_DoBothMixin, ServerBase, unittest.TestCase):
-    def test_hints(self):
-        r = TransitReceiver(self.transit)
-        hints = r.get_direct_hints()
-        self.assertTrue(len(hints), hints)
-
-    @inlineCallbacks
-    def test_direct_to_receiver(self):
-        s = TransitSender(self.transit)
-        r = TransitReceiver(self.transit)
-        key = b"\x00"*32
-
-        # force the connection to be sender->receiver
-        s.set_transit_key(key)
-        # only use 127.0.0.1
-        hint = u"tcp:127.0.0.1:%d" % r.listener.server_address[1]
-        s.add_their_direct_hints([hint])
-        s.add_their_relay_hints([])
-        r.set_transit_key(key)
-        r.add_their_direct_hints([])
-        r.add_their_relay_hints([])
-
-        # it'd be nice to factor this chunk out with 'yield from', but that
-        # didn't appear until python-3.3, and isn't in py2 at all.
-        (sp, rp) = yield self.doBoth([s.connect], [r.connect])
-        yield deferToThread(sp.send_record, b"01234")
-        rec = yield deferToThread(rp.receive_record)
-        self.assertEqual(rec, b"01234")
-        yield deferToThread(sp.close)
-        yield deferToThread(rp.close)
-
-    @inlineCallbacks
-    def test_direct_to_sender(self):
-        s = TransitSender(self.transit)
-        r = TransitReceiver(self.transit)
-        key = b"\x00"*32
-
-        # force the connection to be receiver->sender
-        s.set_transit_key(key)
-        s.add_their_direct_hints([])
-        s.add_their_relay_hints([])
-        r.set_transit_key(key)
-        hint = u"tcp:127.0.0.1:%d" % s.listener.server_address[1]
-        r.add_their_direct_hints([hint])
-        r.add_their_relay_hints([])
-
-        (sp, rp) = yield self.doBoth([s.connect], [r.connect])
-        yield deferToThread(sp.send_record, b"01234")
-        rec = yield deferToThread(rp.receive_record)
-        self.assertEqual(rec, b"01234")
-        yield deferToThread(sp.close)
-        yield deferToThread(rp.close)
-
-    @inlineCallbacks
-    def test_relay(self):
-        s = TransitSender(self.transit)
-        r = TransitReceiver(self.transit)
-        key = b"\x00"*32
-        # force the connection to use the relay by not revealing direct hints
-        s.set_transit_key(key)
-        s.add_their_direct_hints([])
-        s.add_their_relay_hints(r.get_relay_hints())
-        r.set_transit_key(key)
-        r.add_their_direct_hints([])
-        r.add_their_relay_hints(s.get_relay_hints())
-
-        (sp, rp) = yield self.doBoth([s.connect], [r.connect])
-        yield deferToThread(sp.send_record, b"01234")
-        rec = yield deferToThread(rp.receive_record)
-        self.assertEqual(rec, b"01234")
-        yield deferToThread(sp.close)
-        yield deferToThread(rp.close)
-        # TODO: this may be racy if we don't poll the server to make sure
-        # it's witnessed the first connection closing before querying the DB
-        #import time
-        #yield deferToThread(time.sleep, 1)
-
-        # check the transit relay's DB, make sure it counted the bytes
-        db = self._transit_server._db
-        c = db.execute("SELECT * FROM `usage` WHERE `type`=?", (u"transit",))
-        rows = c.fetchall()
-        self.assertEqual(len(rows), 1)
-        row = rows[0]
-        self.assertEqual(row["result"], u"happy")
-        # Sender first writes relay_handshake and waits for OK, but that's
-        # not counted by the transit server. Then sender writes
-        # sender_handshake and waits for receiver_handshake. Then sender
-        # writes GO and the body. Body is length-prefixed SecretBox, so
-        # includes 4-byte length, 24-byte nonce, and 16-byte MAC.
-        sender_count = (len(build_sender_handshake(b""))+
-                        len(b"go\n")+
-                        4+24+len(b"01234")+16)
-        # Receiver first writes relay_handshake and waits for OK, but that's
-        # not counted. Then receiver writes receiver_handshake and waits for
-        # sender_handshake+GO.
-        receiver_count = len(build_receiver_handshake(b""))
-        self.assertEqual(row["total_bytes"], sender_count+receiver_count)
diff --git a/src/wormhole/test/test_scripts.py b/src/wormhole/test/test_scripts.py
index 2939f67..e5c0847 100644
--- a/src/wormhole/test/test_scripts.py
+++ b/src/wormhole/test/test_scripts.py
@@ -4,12 +4,10 @@ from twisted.trial import unittest
 from twisted.python import procutils, log
 from twisted.internet.utils import getProcessOutputAndValue
 from twisted.internet.defer import inlineCallbacks
-from twisted.internet.threads import deferToThread
 from .. import __version__
 from .common import ServerBase
-from ..scripts import (runner, cmd_send_blocking, cmd_send_twisted,
-                       cmd_receive_blocking, cmd_receive_twisted)
-from ..scripts.send_common import build_phase1_data
+from ..scripts import runner, cmd_send, cmd_receive
+from ..scripts.cmd_send import build_phase1_data
 from ..errors import TransferError
 from ..timing import DebugTiming
 
@@ -219,8 +217,7 @@ class PregeneratedCode(ServerBase, ScriptsBase, unittest.TestCase):
 
     @inlineCallbacks
     def _do_test(self, as_subprocess=False,
-                 mode="text", addslash=False, override_filename=False,
-                 sender_twisted=False, receiver_twisted=False):
+                 mode="text", addslash=False, override_filename=False):
         assert mode in ("text", "file", "directory")
         common_args = ["--hide-progress",
                        "--relay-url", self.relayurl,
@@ -314,14 +311,8 @@ class PregeneratedCode(ServerBase, ScriptsBase, unittest.TestCase):
             rargs.stdout = io.StringIO()
             rargs.stderr = io.StringIO()
             rargs.timing = DebugTiming()
-            if sender_twisted:
-                send_d = cmd_send_twisted.send_twisted(sargs)
-            else:
-                send_d = deferToThread(cmd_send_blocking.send_blocking, sargs)
-            if receiver_twisted:
-                receive_d = cmd_receive_twisted.receive_twisted(rargs)
-            else:
-                receive_d = deferToThread(cmd_receive_blocking.receive_blocking, rargs)
+            send_d = cmd_send.send_twisted(sargs)
+            receive_d = cmd_receive.receive_twisted(rargs)
 
             # The sender might fail, leaving the receiver hanging, or vice
             # versa. If either side fails, cancel the other, so it won't
@@ -418,24 +409,11 @@ class PregeneratedCode(ServerBase, ScriptsBase, unittest.TestCase):
         return self._do_test()
     def test_text_subprocess(self):
         return self._do_test(as_subprocess=True)
-    def test_text_twisted_to_blocking(self):
-        return self._do_test(sender_twisted=True)
-    def test_text_blocking_to_twisted(self):
-        return self._do_test(receiver_twisted=True)
-    def test_text_twisted_to_twisted(self):
-        return self._do_test(sender_twisted=True, receiver_twisted=True)
 
     def test_file(self):
         return self._do_test(mode="file")
     def test_file_override(self):
         return self._do_test(mode="file", override_filename=True)
-    def test_file_twisted_to_blocking(self):
-        return self._do_test(mode="file", sender_twisted=True)
-    def test_file_blocking_to_twisted(self):
-        return self._do_test(mode="file", receiver_twisted=True)
-    def test_file_twisted_to_twisted(self):
-        return self._do_test(mode="file",
-                             sender_twisted=True, receiver_twisted=True)
 
     def test_directory(self):
         return self._do_test(mode="directory")
@@ -443,16 +421,3 @@ class PregeneratedCode(ServerBase, ScriptsBase, unittest.TestCase):
         return self._do_test(mode="directory", addslash=True)
     def test_directory_override(self):
         return self._do_test(mode="directory", override_filename=True)
-    def test_directory_twisted_to_blocking(self):
-        return self._do_test(mode="directory", sender_twisted=True)
-    def test_directory_twisted_to_blocking_addslash(self):
-        return self._do_test(mode="directory", addslash=True,
-                             sender_twisted=True)
-    def test_directory_blocking_to_twisted(self):
-        return self._do_test(mode="directory", receiver_twisted=True)
-    def test_directory_twisted_to_twisted(self):
-        return self._do_test(mode="directory",
-                             sender_twisted=True, receiver_twisted=True)
-    def test_directory_twisted_to_twisted_addslash(self):
-        return self._do_test(mode="directory", addslash=True,
-                             sender_twisted=True, receiver_twisted=True)
diff --git a/src/wormhole/test/test_server.py b/src/wormhole/test/test_server.py
index 63dd643..09bea1e 100644
--- a/src/wormhole/test/test_server.py
+++ b/src/wormhole/test/test_server.py
@@ -1,10 +1,12 @@
 from __future__ import print_function
 import json
 import requests
+from binascii import hexlify
 from six.moves.urllib_parse import urlencode
 from twisted.trial import unittest
-from twisted.internet import reactor, defer
+from twisted.internet import protocol, reactor, defer
 from twisted.internet.threads import deferToThread
+from twisted.internet.endpoints import clientFromString, connectProtocol
 from twisted.web.client import getPage, Agent, readBody
 from .. import __version__
 from .common import ServerBase
@@ -434,7 +436,30 @@ class Summary(unittest.TestCase):
         self.failUnlessEqual(c._summarize(make_moods(None, "scary"), 41),
                              (1, "scary", 40, 9))
 
-class Transit(unittest.TestCase):
+class Accumulator(protocol.Protocol):
+    def __init__(self):
+        self.data = b""
+        self.count = 0
+        self._wait = None
+    def waitForBytes(self, more):
+        assert self._wait is None
+        self.count = more
+        self._wait = defer.Deferred()
+        self._check_done()
+        return self._wait
+    def dataReceived(self, data):
+        self.data = self.data + data
+        self._check_done()
+    def _check_done(self):
+        if self._wait and len(self.data) >= self.count:
+            d = self._wait
+            self._wait = None
+            d.callback(self)
+    def connectionLost(self, why):
+        if self._wait:
+            self._wait.errback(RuntimeError("closed"))
+
+class Transit(ServerBase, unittest.TestCase):
     def test_blur_size(self):
         blur = transit_server.blur_size
         self.failUnlessEqual(blur(0), 0)
@@ -453,3 +478,62 @@ class Transit(unittest.TestCase):
         self.failUnlessEqual(blur(1100e6), 1100e6)
         self.failUnlessEqual(blur(1150e6), 1200e6)
 
+    @defer.inlineCallbacks
+    def test_basic(self):
+        ep = clientFromString(reactor, self.transit)
+        a1 = yield connectProtocol(ep, Accumulator())
+        a2 = yield connectProtocol(ep, Accumulator())
+
+        token1 = b"\x00"*32
+        a1.transport.write(b"please relay " + hexlify(token1) + b"\n")
+        a2.transport.write(b"please relay " + hexlify(token1) + b"\n")
+
+        # a correct handshake yields an ack, after which we can send
+        exp = b"ok\n"
+        yield a1.waitForBytes(len(exp))
+        self.assertEqual(a1.data, exp)
+        s1 = b"data1"
+        a1.transport.write(s1)
+
+        exp = b"ok\n"
+        yield a2.waitForBytes(len(exp))
+        self.assertEqual(a2.data, exp)
+
+        # all data they sent after the handshake should be given to us
+        exp = b"ok\n"+s1
+        yield a2.waitForBytes(len(exp))
+        self.assertEqual(a2.data, exp)
+
+        a1.transport.loseConnection()
+        a2.transport.loseConnection()
+
+    @defer.inlineCallbacks
+    def test_bad_handshake(self):
+        ep = clientFromString(reactor, self.transit)
+        a1 = yield connectProtocol(ep, Accumulator())
+
+        token1 = b"\x00"*32
+        # the server waits for the exact number of bytes in the expected
+        # handshake message. to trigger "bad handshake", we must match.
+        a1.transport.write(b"please DELAY " + hexlify(token1) + b"\n")
+
+        exp = b"bad handshake\n"
+        yield a1.waitForBytes(len(exp))
+        self.assertEqual(a1.data, exp)
+
+        a1.transport.loseConnection()
+
+    @defer.inlineCallbacks
+    def test_impatience(self):
+        ep = clientFromString(reactor, self.transit)
+        a1 = yield connectProtocol(ep, Accumulator())
+
+        token1 = b"\x00"*32
+        # sending too many bytes is impatience.
+        a1.transport.write(b"please RELAY NOWNOW " + hexlify(token1) + b"\n")
+
+        exp = b"impatient\n"
+        yield a1.waitForBytes(len(exp))
+        self.assertEqual(a1.data, exp)
+
+        a1.transport.loseConnection()
diff --git a/src/wormhole/test/test_transit.py b/src/wormhole/test/test_transit.py
deleted file mode 100644
index 0ebb750..0000000
--- a/src/wormhole/test/test_transit.py
+++ /dev/null
@@ -1,90 +0,0 @@
-from __future__ import print_function
-from binascii import hexlify
-from twisted.trial import unittest
-from twisted.internet import protocol, defer, reactor
-from twisted.internet.endpoints import clientFromString, connectProtocol
-from .common import ServerBase
-
-class Accumulator(protocol.Protocol):
-    def __init__(self):
-        self.data = b""
-        self.count = 0
-        self._wait = None
-    def waitForBytes(self, more):
-        assert self._wait is None
-        self.count = more
-        self._wait = defer.Deferred()
-        self._check_done()
-        return self._wait
-    def dataReceived(self, data):
-        self.data = self.data + data
-        self._check_done()
-    def _check_done(self):
-        if self._wait and len(self.data) >= self.count:
-            d = self._wait
-            self._wait = None
-            d.callback(self)
-    def connectionLost(self, why):
-        if self._wait:
-            self._wait.errback(RuntimeError("closed"))
-
-class Transit(ServerBase, unittest.TestCase):
-    @defer.inlineCallbacks
-    def test_basic(self):
-        ep = clientFromString(reactor, self.transit)
-        a1 = yield connectProtocol(ep, Accumulator())
-        a2 = yield connectProtocol(ep, Accumulator())
-
-        token1 = b"\x00"*32
-        a1.transport.write(b"please relay " + hexlify(token1) + b"\n")
-        a2.transport.write(b"please relay " + hexlify(token1) + b"\n")
-
-        # a correct handshake yields an ack, after which we can send
-        exp = b"ok\n"
-        yield a1.waitForBytes(len(exp))
-        self.assertEqual(a1.data, exp)
-        s1 = b"data1"
-        a1.transport.write(s1)
-
-        exp = b"ok\n"
-        yield a2.waitForBytes(len(exp))
-        self.assertEqual(a2.data, exp)
-
-        # all data they sent after the handshake should be given to us
-        exp = b"ok\n"+s1
-        yield a2.waitForBytes(len(exp))
-        self.assertEqual(a2.data, exp)
-
-        a1.transport.loseConnection()
-        a2.transport.loseConnection()
-
-    @defer.inlineCallbacks
-    def test_bad_handshake(self):
-        ep = clientFromString(reactor, self.transit)
-        a1 = yield connectProtocol(ep, Accumulator())
-
-        token1 = b"\x00"*32
-        # the server waits for the exact number of bytes in the expected
-        # handshake message. to trigger "bad handshake", we must match.
-        a1.transport.write(b"please DELAY " + hexlify(token1) + b"\n")
-
-        exp = b"bad handshake\n"
-        yield a1.waitForBytes(len(exp))
-        self.assertEqual(a1.data, exp)
-
-        a1.transport.loseConnection()
-
-    @defer.inlineCallbacks
-    def test_impatience(self):
-        ep = clientFromString(reactor, self.transit)
-        a1 = yield connectProtocol(ep, Accumulator())
-
-        token1 = b"\x00"*32
-        # sending too many bytes is impatience.
-        a1.transport.write(b"please RELAY NOWNOW " + hexlify(token1) + b"\n")
-
-        exp = b"impatient\n"
-        yield a1.waitForBytes(len(exp))
-        self.assertEqual(a1.data, exp)
-
-        a1.transport.loseConnection()
diff --git a/src/wormhole/transit_common.py b/src/wormhole/transit_common.py
deleted file mode 100644
index eb18c92..0000000
--- a/src/wormhole/transit_common.py
+++ /dev/null
@@ -1,87 +0,0 @@
-import re
-from binascii import hexlify
-from .util.hkdf import HKDF
-
-class TransitError(Exception):
-    pass
-
-class BadHandshake(Exception):
-    pass
-
-class TransitClosed(TransitError):
-    pass
-
-class BadNonce(TransitError):
-    pass
-
-# The beginning of each TCP connection consists of the following handshake
-# messages. The sender transmits the same text regardless of whether it is on
-# the initiating/connecting end of the TCP connection, or on the
-# listening/accepting side. Same for the receiver.
-#
-#  sender -> receiver: transit sender TXID_HEX ready\n\n
-#  receiver -> sender: transit receiver RXID_HEX ready\n\n
-#
-# Any deviations from this result in the socket being closed. The handshake
-# messages are designed to provoke an invalid response from other sorts of
-# servers (HTTP, SMTP, echo).
-#
-# If the sender is satisfied with the handshake, and this is the first socket
-# to complete negotiation, the sender does:
-#
-#  sender -> receiver: go\n
-#
-# and the next byte on the wire will be from the application.
-#
-# If this is not the first socket, the sender does:
-#
-#  sender -> receiver: nevermind\n
-#
-# and closes the socket.
-
-# So the receiver looks for "transit sender TXID_HEX ready\n\ngo\n" and hangs
-# up upon the first wrong byte. The sender lookgs for "transit receiver
-# RXID_HEX ready\n\n" and then makes a first/not-first decision about sending
-# "go\n" or "nevermind\n"+close().
-
-def build_receiver_handshake(key):
-    hexid = HKDF(key, 32, CTXinfo=b"transit_receiver")
-    return b"transit receiver "+hexlify(hexid)+b" ready\n\n"
-
-def build_sender_handshake(key):
-    hexid = HKDF(key, 32, CTXinfo=b"transit_sender")
-    return b"transit sender "+hexlify(hexid)+b" ready\n\n"
-
-def build_relay_handshake(key):
-    token = HKDF(key, 32, CTXinfo=b"transit_relay_token")
-    return b"please relay "+hexlify(token)+b"\n"
-
-# The hint format is: TYPE,VALUE= /^([a-zA-Z0-9]+):(.*)$/ . VALUE depends
-# upon TYPE, and it can have more colons in it. For TYPE=tcp (the only one
-# currently defined), ADDR,PORT = /^(.*):(\d+)$/ , so ADDR can have colons.
-# ADDR can be a hostname, ipv4 dotted-quad, or ipv6 colon-hex. If the hint
-# publisher wants anonymity, their only hint's ADDR will end in .onion .
-
-def parse_hint_tcp(hint):
-    assert isinstance(hint, type(u""))
-    # return tuple or None for an unparseable hint
-    mo = re.search(r'^([a-zA-Z0-9]+):(.*)$', hint)
-    if not mo:
-        print("unparseable hint '%s'" % (hint,))
-        return None
-    hint_type = mo.group(1)
-    if hint_type != "tcp":
-        print("unknown hint type '%s' in '%s'" % (hint_type, hint))
-        return None
-    hint_value = mo.group(2)
-    mo = re.search(r'^(.*):(\d+)$', hint_value)
-    if not mo:
-        print("unparseable TCP hint '%s'" % (hint,))
-        return None
-    hint_host = mo.group(1)
-    try:
-        hint_port = int(mo.group(2))
-    except ValueError:
-        print("non-numeric port in TCP hint '%s'" % (hint,))
-        return None
-    return hint_host, hint_port
diff --git a/src/wormhole/twisted/transit.py b/src/wormhole/twisted/transit.py
index cc8bed8..199b361 100644
--- a/src/wormhole/twisted/transit.py
+++ b/src/wormhole/twisted/transit.py
@@ -1,5 +1,5 @@
 from __future__ import print_function
-import sys, time, socket, collections
+import re, sys, time, socket, collections
 from binascii import hexlify, unhexlify
 from zope.interface import implementer
 from twisted.python.runtime import platformType
@@ -12,11 +12,6 @@ from ..util import ipaddrs
 from ..util.hkdf import HKDF
 from ..errors import UsageError
 from ..timing import DebugTiming
-from ..transit_common import (BadHandshake,
-                              BadNonce,
-                              build_receiver_handshake,
-                              build_sender_handshake,
-                              build_relay_handshake)
 
 def debug(msg):
     if False:
@@ -24,6 +19,90 @@ def debug(msg):
 def since(start):
     return time.time() - start
 
+class TransitError(Exception):
+    pass
+
+class BadHandshake(Exception):
+    pass
+
+class TransitClosed(TransitError):
+    pass
+
+class BadNonce(TransitError):
+    pass
+
+# The beginning of each TCP connection consists of the following handshake
+# messages. The sender transmits the same text regardless of whether it is on
+# the initiating/connecting end of the TCP connection, or on the
+# listening/accepting side. Same for the receiver.
+#
+#  sender -> receiver: transit sender TXID_HEX ready\n\n
+#  receiver -> sender: transit receiver RXID_HEX ready\n\n
+#
+# Any deviations from this result in the socket being closed. The handshake
+# messages are designed to provoke an invalid response from other sorts of
+# servers (HTTP, SMTP, echo).
+#
+# If the sender is satisfied with the handshake, and this is the first socket
+# to complete negotiation, the sender does:
+#
+#  sender -> receiver: go\n
+#
+# and the next byte on the wire will be from the application.
+#
+# If this is not the first socket, the sender does:
+#
+#  sender -> receiver: nevermind\n
+#
+# and closes the socket.
+
+# So the receiver looks for "transit sender TXID_HEX ready\n\ngo\n" and hangs
+# up upon the first wrong byte. The sender lookgs for "transit receiver
+# RXID_HEX ready\n\n" and then makes a first/not-first decision about sending
+# "go\n" or "nevermind\n"+close().
+
+def build_receiver_handshake(key):
+    hexid = HKDF(key, 32, CTXinfo=b"transit_receiver")
+    return b"transit receiver "+hexlify(hexid)+b" ready\n\n"
+
+def build_sender_handshake(key):
+    hexid = HKDF(key, 32, CTXinfo=b"transit_sender")
+    return b"transit sender "+hexlify(hexid)+b" ready\n\n"
+
+def build_relay_handshake(key):
+    token = HKDF(key, 32, CTXinfo=b"transit_relay_token")
+    return b"please relay "+hexlify(token)+b"\n"
+
+# The hint format is: TYPE,VALUE= /^([a-zA-Z0-9]+):(.*)$/ . VALUE depends
+# upon TYPE, and it can have more colons in it. For TYPE=tcp (the only one
+# currently defined), ADDR,PORT = /^(.*):(\d+)$/ , so ADDR can have colons.
+# ADDR can be a hostname, ipv4 dotted-quad, or ipv6 colon-hex. If the hint
+# publisher wants anonymity, their only hint's ADDR will end in .onion .
+
+def parse_hint_tcp(hint):
+    assert isinstance(hint, type(u""))
+    # return tuple or None for an unparseable hint
+    mo = re.search(r'^([a-zA-Z0-9]+):(.*)$', hint)
+    if not mo:
+        print("unparseable hint '%s'" % (hint,))
+        return None
+    hint_type = mo.group(1)
+    if hint_type != "tcp":
+        print("unknown hint type '%s' in '%s'" % (hint_type, hint))
+        return None
+    hint_value = mo.group(2)
+    mo = re.search(r'^(.*):(\d+)$', hint_value)
+    if not mo:
+        print("unparseable TCP hint '%s'" % (hint,))
+        return None
+    hint_host = mo.group(1)
+    try:
+        hint_port = int(mo.group(2))
+    except ValueError:
+        print("non-numeric port in TCP hint '%s'" % (hint,))
+        return None
+    return hint_host, hint_port
+
 TIMEOUT=15
 
 @implementer(interfaces.IProducer, interfaces.IConsumer)
@@ -684,7 +763,7 @@ class Common:
         return d
 
     def _endpoint_from_hint(self, hint):
-        # TODO: use transit_common.parse_hint_tcp
+        # TODO: use parse_hint_tcp
         if ":" not in hint:
             return None
         pieces = hint.split(":")
diff --git a/src/wormhole/twisted/util.py b/src/wormhole/twisted/util.py
deleted file mode 100644
index 182fc34..0000000
--- a/src/wormhole/twisted/util.py
+++ /dev/null
@@ -1,21 +0,0 @@
-from twisted.internet import defer, protocol, endpoints, reactor
-
-def allocate_port():
-    ep = endpoints.serverFromString(reactor, "tcp:0:interface=127.0.0.1")
-    d = ep.listen(protocol.Factory())
-    def _listening(lp):
-        port = lp.getHost().port
-        d2 = lp.stopListening()
-        d2.addCallback(lambda _: port)
-        return d2
-    d.addCallback(_listening)
-    return d
-
-def allocate_ports():
-    d = defer.DeferredList([allocate_port(), allocate_port()])
-    def _done(results):
-        port1 = results[0][1]
-        port2 = results[1][1]
-        return (port1, port2)
-    d.addCallback(_done)
-    return d
diff --git a/src/wormhole/util/observer.py b/src/wormhole/util/observer.py
deleted file mode 100644
index 25ce716..0000000
--- a/src/wormhole/util/observer.py
+++ /dev/null
@@ -1,50 +0,0 @@
-# -*- test-case-name: foolscap.test_observer -*-
-
-# many thanks to AllMyData for contributing the initial version of this code
-
-from twisted.internet import defer
-from foolscap import eventual
-
-class OneShotObserverList(object):
-    """A one-shot event distributor.
-
-    Subscribers can get a Deferred that will fire with the results of the
-    event once it finally occurs. The caller does not need to know whether
-    the event has happened yet or not: they get a Deferred in either case.
-
-    The Deferreds returned to subscribers are guaranteed to not fire in the
-    current reactor turn; instead, eventually() is used to fire them in a
-    later turn. Look at Mark Miller's 'Concurrency Among Strangers' paper on
-    erights.org for a description of why this property is useful.
-
-    I can only be fired once."""
-
-    def __init__(self):
-        self._fired = False
-        self._result = None
-        self._watchers = []
-        self.__repr__ = self._unfired_repr
-
-    def _unfired_repr(self):
-        return "<OneShotObserverList [%s]>" % (self._watchers, )
-
-    def _fired_repr(self):
-        return "<OneShotObserverList -> %s>" % (self._result, )
-
-    def whenFired(self):
-        if self._fired:
-            return eventual.fireEventually(self._result)
-        d = defer.Deferred()
-        self._watchers.append(d)
-        return d
-
-    def fire(self, result):
-        assert not self._fired
-        self._fired = True
-        self._result = result
-
-        for w in self._watchers:
-            eventual.eventually(w.callback, result)
-        del self._watchers
-        self.__repr__ = self._fired_repr
-
diff --git a/tox.ini b/tox.ini
index 6caebfc..ebef7a7 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,12 +7,6 @@
 envlist = py27,py33,py34,py35
 skip_missing_interpreters = True
 
-# There's a race-condition bug in Twisted-15.5.0 (#8014, fixed in trunk) that
-# manifests as various intermittent magic-wormhole test failures that always
-# include twisted.internet.endpoints "iterateEndpoint" or "checkDone". So run
-# all builds with a copy of Twisted from git 'trunk' until Twisted-16.0.0 is
-# released and we can just depend on that.
-
 # On windows we need "pypiwin32" installed. It's supposedly possible to make
 # Twisted do this by depending upon "twisted[windows]" instead of just
 # "twisted", but when I try this via Appveyor, the extra is ignored.
@@ -24,7 +18,6 @@ skip_missing_interpreters = True
 
 [testenv]
 deps =
-    twisted >= 16.1.0
     pyflakes
     {env:EXTRA_DEPENDENCY:}
 commands =