diff --git a/trezorlib/protocol_v1.py b/trezorlib/protocol_v1.py
index 9bf6b59..e3ef43f 100644
--- a/trezorlib/protocol_v1.py
+++ b/trezorlib/protocol_v1.py
@@ -39,7 +39,7 @@ class ProtocolV1(object):
 
         while data:
             # Report ID, data padded to 63 bytes
-            chunk = b'?' + data[:REPLEN-1]
+            chunk = b'?' + data[:REPLEN - 1]
             chunk = chunk.ljust(REPLEN, bytes([0x00]))
             transport.write_chunk(chunk)
             data = data[63:]
diff --git a/trezorlib/protocol_v2.py b/trezorlib/protocol_v2.py
index cea18ea..8e64281 100644
--- a/trezorlib/protocol_v2.py
+++ b/trezorlib/protocol_v2.py
@@ -124,4 +124,4 @@ class ProtocolV2(object):
             raise Exception('Cannot parse header')
         if magic != 0x03:
             raise Exception('Unexpected magic character')
-        return session
\ No newline at end of file
+        return session
diff --git a/trezorlib/transport.py b/trezorlib/transport.py
index 3bf6dbd..23c27bb 100644
--- a/trezorlib/transport.py
+++ b/trezorlib/transport.py
@@ -39,4 +39,4 @@ class Transport(object):
         raise NotImplementedError
 
     def close(self):
-        raise NotImplementedError
\ No newline at end of file
+        raise NotImplementedError