diff --git a/rnsh/protocol.py b/rnsh/protocol.py
index a833ad8..486b9e3 100644
--- a/rnsh/protocol.py
+++ b/rnsh/protocol.py
@@ -10,6 +10,7 @@ from types import TracebackType
 from typing import Type, Callable, TypeVar, Tuple
 import RNS
 from RNS.vendor import umsgpack
+from RNS.Buffer import StreamDataMessage as RNSStreamDataMessage
 import rnsh.retry
 import abc
 import contextlib
@@ -81,30 +82,12 @@ class ExecuteCommandMesssage(RNS.MessageBase):
             self.cols, self.hpix, self.vpix = umsgpack.unpackb(raw)
 
 
-class StreamDataMessage(RNS.MessageBase):
+# Create a version of RNS.Buffer.StreamDataMessage that we control
+class StreamDataMessage(RNSStreamDataMessage):
     MSGTYPE = _make_MSGTYPE(4)
     STREAM_ID_STDIN  = 0
     STREAM_ID_STDOUT = 1
     STREAM_ID_STDERR = 2
-    OVERHEAD = 0
-
-    def __init__(self, stream_id: int = None, data: bytes = None, eof: bool = False):
-        super().__init__()
-        self.stream_id = stream_id
-        self.data = data
-        self.eof = eof
-
-    def pack(self) -> bytes:
-        return umsgpack.packb((self.stream_id, self.eof, bytes(self.data)))
-
-    def unpack(self, raw):
-        self.stream_id, self.eof, self.data = umsgpack.unpackb(raw)
-
-
-_link_sized_bytes = ("\0"*RNS.Link.MDU).encode("utf-8")
-StreamDataMessage.OVERHEAD = len(StreamDataMessage(stream_id=0, data=_link_sized_bytes, eof=True).pack()) \
-                             - len(_link_sized_bytes)
-_link_sized_bytes = None
 
 
 class VersionInfoMessage(RNS.MessageBase):
diff --git a/rnsh/session.py b/rnsh/session.py
index b79e155..1c948e7 100644
--- a/rnsh/session.py
+++ b/rnsh/session.py
@@ -210,7 +210,7 @@ class ListenerSession:
             elif not self.channel.is_ready_to_send():
                 return False
             elif len(self.stderr_buf) > 0:
-                mdu = self.channel.MDU - protocol.StreamDataMessage.OVERHEAD
+                mdu = protocol.StreamDataMessage.MAX_DATA_LEN
                 data = self.stderr_buf[:mdu]
                 self.stderr_buf = self.stderr_buf[mdu:]
                 send_eof = self.process.stderr_eof and len(data) == 0 and not self.stderr_eof_sent
@@ -222,7 +222,7 @@ class ListenerSession:
                     self.stderr_eof_sent = True
                 return True
             elif len(self.stdout_buf) > 0:
-                mdu = self.channel.MDU - protocol.StreamDataMessage.OVERHEAD
+                mdu = protocol.StreamDataMessage.MAX_DATA_LEN
                 data = self.stdout_buf[:mdu]
                 self.stdout_buf = self.stdout_buf[mdu:]
                 send_eof = self.process.stdout_eof and len(data) == 0 and not self.stdout_eof_sent