diff --git a/src/python/devtest/os/conn/Serial.py b/src/python/devtest/os/conn/Serial.py
index 195b291..92e93f1 100644
--- a/src/python/devtest/os/conn/Serial.py
+++ b/src/python/devtest/os/conn/Serial.py
@@ -249,13 +249,13 @@ class Serial(Connection): # export
                 #self._fd = os.open(self._path, self._flags)
                 limit = asyncio.streams._DEFAULT_LIMIT
                 if mode == os.O_WRONLY or mode == os.O_RDWR:
-                    self._wr_stream = os.fdopen(self._fd, mode='wb', buffering=1)
+                    self._wr_stream = os.fdopen(self._fd, mode='wb')
                     #transp, proto = await self.pair.env.eloop.connect_write_pipe(Fifos.Protocol, self._wr_stream)
                     #self._stream_writer = asyncio.streams.StreamWriter(transp, proto, None, loop)
                     transp, proto = await loop.connect_write_pipe(lambda: asyncio.streams.FlowControlMixin(loop=loop), self._wr_stream)
                     self._stream_writer = asyncio.streams.StreamWriter(transp, proto, None, loop)
                 if mode == os.O_RDONLY or mode == os.O_RDWR:
-                    self._rd_stream = os.fdopen(self._fd, mode='rb', buffering=1)
+                    self._rd_stream = os.fdopen(self._fd, mode='rb')
                     #transp, proto = await self.pair.env.eloop.connect_read_pipe(Fifos.Protocol, self._rd_stream)
                     #self._stream_reader = asyncio.streams.StreamReader(transp, proto, None, loop)
                     self._stream_reader = asyncio.StreamReader(limit=limit, loop=loop)