diff --git a/mercurial/wireprotoserver.py b/mercurial/wireprotoserver.py
--- a/mercurial/wireprotoserver.py
+++ b/mercurial/wireprotoserver.py
@@ -336,19 +336,11 @@
 
     return ''
 
-class sshserver(baseprotocolhandler):
-    def __init__(self, ui, repo):
+class sshprotocolhandler(baseprotocolhandler):
+    def __init__(self, ui, fin, fout):
         self._ui = ui
-        self._repo = repo
-        self._fin = ui.fin
-        self._fout = ui.fout
-
-        hook.redirect(True)
-        ui.fout = repo.ui.fout = ui.ferr
-
-        # Prevent insertion/deletion of CRs
-        util.setbinary(self._fin)
-        util.setbinary(self._fout)
+        self._fin = fin
+        self._fout = fout
 
     @property
     def name(self):
@@ -409,11 +401,6 @@
         self._fout.write('\n')
         self._fout.flush()
 
-    def serve_forever(self):
-        while self.serve_one():
-            pass
-        sys.exit(0)
-
     _handlers = {
         str: _sendresponse,
         wireproto.streamres: _sendstream,
@@ -423,15 +410,38 @@
         wireproto.ooberror: _sendooberror,
     }
 
-    def serve_one(self):
-        cmd = self._fin.readline()[:-1]
-        if cmd and wireproto.commands.commandavailable(cmd, self):
-            rsp = wireproto.dispatch(self._repo, self, cmd)
-            self._handlers[rsp.__class__](self, rsp)
-        elif cmd:
-            self._sendresponse("")
-        return cmd != ''
-
     def _client(self):
         client = encoding.environ.get('SSH_CLIENT', '').split(' ', 1)[0]
         return 'remote:ssh:' + client
+
+class sshserver(object):
+    def __init__(self, ui, repo):
+        self._ui = ui
+        self._repo = repo
+        self._fin = ui.fin
+        self._fout = ui.fout
+
+        hook.redirect(True)
+        ui.fout = repo.ui.fout = ui.ferr
+
+        # Prevent insertion/deletion of CRs
+        util.setbinary(self._fin)
+        util.setbinary(self._fout)
+
+        self._proto = sshprotocolhandler(self._ui, self._fin, self._fout)
+
+    def serve_forever(self):
+        while self.serve_one():
+            pass
+        sys.exit(0)
+
+    def serve_one(self):
+        # TODO improve boundary between transport layer and protocol handler.
+        cmd = self._fin.readline()[:-1]
+        if cmd and wireproto.commands.commandavailable(cmd, self._proto):
+            rsp = wireproto.dispatch(self._repo, self._proto, cmd)
+            self._proto._handlers[rsp.__class__](self._proto, rsp)
+        elif cmd:
+            self._proto._sendresponse("")
+
+        return cmd != ''
diff --git a/tests/sshprotoext.py b/tests/sshprotoext.py
--- a/tests/sshprotoext.py
+++ b/tests/sshprotoext.py
@@ -45,11 +45,11 @@
         l = self._fin.readline()
         assert l == b'hello\n'
         # Respond to unknown commands with an empty reply.
-        self._sendresponse(b'')
+        self._proto._sendresponse(b'')
         l = self._fin.readline()
         assert l == b'between\n'
-        rsp = wireproto.dispatch(self._repo, self, b'between')
-        self._handlers[rsp.__class__](self, rsp)
+        rsp = wireproto.dispatch(self._repo, self._proto, b'between')
+        self._proto._handlers[rsp.__class__](self._proto, rsp)
 
         super(prehelloserver, self).serve_forever()
 
@@ -73,7 +73,7 @@
 
         # Send the upgrade response.
         self._fout.write(b'upgraded %s %s\n' % (token, name))
-        servercaps = wireproto.capabilities(self._repo, self)
+        servercaps = wireproto.capabilities(self._repo, self._proto)
         rsp = b'capabilities: %s' % servercaps
         self._fout.write(b'%d\n' % len(rsp))
         self._fout.write(rsp)
diff --git a/tests/test-sshserver.py b/tests/test-sshserver.py
--- a/tests/test-sshserver.py
+++ b/tests/test-sshserver.py
@@ -24,7 +24,7 @@
     def assertparse(self, cmd, input, expected):
         server = mockserver(input)
         _func, spec = wireproto.commands[cmd]
-        self.assertEqual(server.getargs(spec), expected)
+        self.assertEqual(server._proto.getargs(spec), expected)
 
 def mockserver(inbytes):
     ui = mockui(inbytes)