diff --git a/trezorlib/client.py b/trezorlib/client.py
index 03053949a..c27fb8393 100644
--- a/trezorlib/client.py
+++ b/trezorlib/client.py
@@ -83,21 +83,14 @@ def get_buttonrequest_value(code):
 
 
 class CallException(Exception):
-    def __init__(self, code, message):
-        super(CallException, self).__init__()
-        self.args = [code, message]
-
-
-class AssertionException(Exception):
-    def __init__(self, code, message):
-        self.args = [code, message]
+    pass
 
 
 class PinException(CallException):
     pass
 
 
-class field(object):
+class field:
     # Decorator extracts single value from
     # protobuf object. If the field is not
     # present, raises an exception.
@@ -105,13 +98,14 @@ class field(object):
         self.field = field
 
     def __call__(self, f):
+        @functools.wraps(f)
         def wrapped_f(*args, **kwargs):
             ret = f(*args, **kwargs)
             return getattr(ret, self.field)
         return wrapped_f
 
 
-class expect(object):
+class expect:
     # Decorator checks if the method
     # returned one of expected protobuf messages
     # or raises an exception
@@ -119,6 +113,7 @@ class expect(object):
         self.expected = expected
 
     def __call__(self, f):
+        @functools.wraps(f)
         def wrapped_f(*args, **kwargs):
             ret = f(*args, **kwargs)
             if not isinstance(ret, self.expected):
@@ -130,6 +125,7 @@ class expect(object):
 def session(f):
     # Decorator wraps a BaseClient method
     # with session activation / deactivation
+    @functools.wraps(f)
     def wrapped_f(*args, **kwargs):
         client = args[0]
         client.transport.session_begin()
@@ -388,19 +384,19 @@ class DebugLinkMixin(object):
             try:
                 expected = self.expected_responses.pop(0)
             except IndexError:
-                raise AssertionException(proto.FailureType.UnexpectedMessage,
-                                         "Got %s, but no message has been expected" % repr(msg))
+                raise AssertionError(proto.FailureType.UnexpectedMessage,
+                                     "Got %s, but no message has been expected" % repr(msg))
 
             if msg.__class__ != expected.__class__:
-                raise AssertionException(proto.FailureType.UnexpectedMessage,
-                                         "Expected %s, got %s" % (repr(expected), repr(msg)))
+                raise AssertionError(proto.FailureType.UnexpectedMessage,
+                                     "Expected %s, got %s" % (repr(expected), repr(msg)))
 
             for field, value in expected.__dict__.items():
                 if value is None or value == []:
                     continue
                 if getattr(msg, field) != value:
-                    raise AssertionException(proto.FailureType.UnexpectedMessage,
-                                             "Expected %s, got %s" % (repr(expected), repr(msg)))
+                    raise AssertionError(proto.FailureType.UnexpectedMessage,
+                                         "Expected %s, got %s" % (repr(expected), repr(msg)))
 
     def callback_ButtonRequest(self, msg):
         self.DEBUG("ButtonRequest code: " + get_buttonrequest_value(msg.code))