diff --git a/bitkeylib/transport.py b/bitkeylib/transport.py
index aaf13ee..ad13c3f 100644
--- a/bitkeylib/transport.py
+++ b/bitkeylib/transport.py
@@ -1,25 +1,28 @@
 import struct
 import mapping
 
+class NotImplementedException(Exception):
+    pass
+
 class Transport(object):
     def __init__(self, device, *args, **kwargs):
         self.device = device
         self._open()
     
     def _open(self):
-        raise NotImplemented
+        raise NotImplementedException("Not implemented")
     
     def _close(self):
-        raise NotImplemented
+        raise NotImplementedException("Not implemented")
     
     def _write(self, msg):
-        raise NotImplemented
+        raise NotImplementedException("Not implemented")
     
     def _read(self):
-        raise NotImplemented
+        raise NotImplementedException("Not implemented")
     
     def ready_to_read(self):
-        raise NotImplemented
+        raise NotImplementedException("Not implemented")
         
     def close(self):
         self._close()
diff --git a/bitkeylib/transport_fake.py b/bitkeylib/transport_fake.py
index 1954c96..a56f442 100644
--- a/bitkeylib/transport_fake.py
+++ b/bitkeylib/transport_fake.py
@@ -2,7 +2,7 @@
 
 # Local serial port loopback: socat PTY,link=COM8 PTY,link=COM9
 
-from transport import Transport
+from transport import Transport, NotImplementedException
 
 class FakeTransport(Transport):
     def __init__(self, device, *args, **kwargs):
@@ -21,4 +21,4 @@ class FakeTransport(Transport):
         pass
         
     def _read(self):
-        raise NotImplemented
\ No newline at end of file
+        raise NotImplementedException("Not implemented")
\ No newline at end of file