diff --git a/trezorlib/client.py b/trezorlib/client.py
index 835a4dc679..846d8cc695 100644
--- a/trezorlib/client.py
+++ b/trezorlib/client.py
@@ -15,8 +15,7 @@ def get_buttonrequest_value(code):
     return [ k for k, v in types.ButtonRequestType.items() if v == code][0]
 
 def pprint(msg):
-    ser = msg.SerializeToString()
-    return "<%s> (%d bytes):\n%s" % (msg.__class__.__name__, len(ser), msg)
+    return "<%s> (%d bytes):\n%s" % (msg.__class__.__name__, msg.ByteSize(), msg)
 
 class CallException(Exception):
     def __init__(self, code, message):
@@ -62,13 +61,23 @@ class BaseClient(object):
         self.transport = transport
         super(BaseClient, self).__init__()  # *args, **kwargs)
 
-    def call(self, msg):
+    def call_raw(self, msg):
         try:
             self.transport.session_begin()
 
             self.transport.write(msg)
             resp = self.transport.read_blocking()
 
+        finally:
+            self.transport.session_end()
+
+        return resp
+
+    def call(self, msg):
+        try:
+            self.transport.session_begin()
+
+            resp = self.call_raw(msg)
             handler_name = "callback_%s" % resp.__class__.__name__
             handler = getattr(self, handler_name, None)
 
@@ -138,8 +147,11 @@ class DebugLinkMixin(object):
         # Always press Yes and provide correct pin
         self.setup_debuglink(True, True)
         
-        # Do not expect any specific ButtonRequest
-        self.set_expected_buttonrequests(None)
+        # Do not expect any specific response from device
+        self.set_expected_responses(None)
+
+        # Use blank passphrase
+        self.set_passphrase('')
 
     def close(self):
         super(DebugLinkMixin, self).close()
@@ -149,33 +161,50 @@ class DebugLinkMixin(object):
     def set_debuglink(self, debug_transport):
         self.debug = DebugLink(debug_transport)
 
-    def set_expected_buttonrequests(self, expected):
-        self.expected_buttonrequests = expected
+    def set_expected_responses(self, expected):
+        self.expected_responses = expected
 
     def setup_debuglink(self, button, pin_correct):
         self.button = button  # True -> YES button, False -> NO button
         self.pin_correct = pin_correct
 
+    def set_passphrase(self, passphrase):
+        self.passphrase = passphrase
+
+    def call_raw(self, msg):
+        resp = super(DebugLinkMixin, self).call_raw(msg)
+        self._check_request(resp)
+        return resp
+
     def call(self, msg):
         print "SENDING", pprint(msg)
         ret = super(DebugLinkMixin, self).call(msg)
         print "RECEIVED", pprint(ret)
+
+        if self.expected_responses != None and len(self.expected_responses):
+            raise Exception("Some of expected responses didn't come from device: %s" % \
+                    [ pprint(x) for x in self.expected_responses ])
         return ret
         
-    def callback_ButtonRequest(self, msg):
-        if self.expected_buttonrequests != None:
+    def _check_request(self, msg):
+        if self.expected_responses != None:
             try:
-                expected = self.expected_buttonrequests.pop(0)
-                if msg.code != expected:
-                    raise CallException(types.Failure_Other,
-                                "Expected %s, got %s" % \
-                                (get_buttonrequest_value(expected),
-                                 get_buttonrequest_value(msg.code)))
+                expected = self.expected_responses.pop(0)
             except IndexError:
                 raise CallException(types.Failure_Other,
-                        "Got %s, but no ButtonRequest has been expected" % \
-                        get_buttonrequest_value(msg.code))
+                        "Got %s, but no message has been expected" % pprint(msg))
 
+            if msg.__class__ != expected.__class__:
+                raise CallException(types.Failure_Other,
+                            "Expected %s, got %s" % (pprint(expected), pprint(msg)))
+
+            fields = expected.ListFields()  # only filled (including extensions)
+            for field, value in fields:
+                if not msg.HasField(field.name) or getattr(msg, field.name) != value:
+                    raise CallException(types.Failure_Other,
+                            "Expected %s, got %s" % (pprint(expected), pprint(msg)))
+            
+    def callback_ButtonRequest(self, msg):
         print "ButtonRequest code:", get_buttonrequest_value(msg.code)
 
         print "Pressing button", self.button
@@ -190,7 +219,8 @@ class DebugLinkMixin(object):
         return proto.PinMatrixAck(pin=pin)
 
     def callback_PassphraseRequest(self, msg):
-        raise Exception("Not implemented yet")
+        print "Provided passphrase: '%s'" % self.passphrase
+        return proto.PassphraseAck(passphrase=self.passphrase)
 
     def callback_WordRequest(self, msg):
         raise Exception("Not implemented yet")