diff --git a/README.md b/README.md
index f8d5167..1629ee1 100644
--- a/README.md
+++ b/README.md
@@ -18,7 +18,7 @@ pip3 install --user -e .
 ## usage
 
 ```
-usage: megacom [-h] [-b BAUD] [-m MODE] [tty]
+usage: megacom [-h] [-b BAUD] [-m MODE] [-l LOGFILE] [tty]
 
 Alternative console-based UART client
 
@@ -29,6 +29,8 @@ optional arguments:
   -h, --help            show this help message and exit
   -b BAUD, --baud BAUD  UART baud rate [115200]
   -m MODE, --mode MODE  UART mode string [8N1]
+  -l LOGFILE, --logfile LOGFILE
+                        file to log to
 ```
 
 ### sudo
diff --git a/megacom/__init__.py b/megacom/__init__.py
index b54b220..2730208 100644
--- a/megacom/__init__.py
+++ b/megacom/__init__.py
@@ -7,7 +7,7 @@ import sys
 import termios
 import tty
 from types import TracebackType
-from typing import Any, List, Optional, Tuple, Type
+from typing import Any, BinaryIO, List, Optional, Tuple, Type
 from typing_extensions import Literal
 
 import serial
@@ -103,7 +103,7 @@ class KeycodeHandler:
         return byte
 
 
-async def megacom(tty: str, baud: int, mode: str) -> None:
+async def megacom(tty: str, baud: int, mode: str, logfile: Optional[str]) -> None:
     (stdin, stdout) = await setup_async()
 
     m = MODE_RE.match(mode)
@@ -114,14 +114,24 @@ async def megacom(tty: str, baud: int, mode: str) -> None:
     parity = MODE_LOOKUP["parity"][m.group(2)]
     stopbits = MODE_LOOKUP["stopbits"][m.group(3)]
 
+    log: Optional[BinaryIO] = None
+    if logfile is not None:
+        try:
+            log = open(logfile, "wb")
+        except Exception as e:
+            sys.stderr.write(f"failed to open log file: {e}\n")
+            sys.exit(1)
+
     loop = asyncio.get_event_loop()
     keycodes = KeycodeHandler()
-    return await megacom_main(stdin, stdout, tty, baud, bytesize, parity, stopbits, loop, keycodes)
+    return await megacom_main(stdin, stdout, tty, baud, bytesize, parity, stopbits, loop, keycodes,
+                              log)
 
 
 async def megacom_main(stdin: asyncio.StreamReader, stdout: asyncio.StreamWriter, tty: str,
                        baud: int, bytesize: Any, parity: Any, stopbits: Any,
-                       loop: asyncio.AbstractEventLoop, keycodes: KeycodeHandler) -> None:
+                       loop: asyncio.AbstractEventLoop, keycodes: KeycodeHandler,
+                       log: Optional[BinaryIO]) -> None:
     printed_fnf = False
 
     while True:
@@ -179,9 +189,11 @@ async def megacom_main(stdin: asyncio.StreamReader, stdout: asyncio.StreamWriter
                 c = keycodes.process(c)
                 if len(c) == 0:
                     continue
-            # else:
-            #     stdout.write(f"\r\nout char: {c}\r\n".encode())
-            #     await stdout.drain()
+            else:
+                # stdout.write(f"\r\nout char: {c}\r\n".encode())
+                # await stdout.drain()
+                if log is not None:
+                    log.write(c)
 
             pout.write(c)
             await pout.drain()
@@ -236,7 +248,7 @@ async def megacom_main(stdin: asyncio.StreamReader, stdout: asyncio.StreamWriter
 
     if do_retry:
         return await megacom_main(stdin, stdout, tty, baud, bytesize, parity, stopbits, loop,
-                                  keycodes)
+                                  keycodes, log)
 
 
 def main() -> None:
@@ -246,7 +258,9 @@ def main() -> None:
                         help="Path to UART device [/dev/ttyUSB0]")
     parser.add_argument("-b", "--baud", type=int, default=115200, help="UART baud rate [115200]")
     parser.add_argument("-m", "--mode", type=str, default="8N1", help="UART mode string [8N1]")
+    parser.add_argument("-l", "--logfile", type=str, default="", help="file to log to")
     args = parser.parse_args()
 
     with TtyRaw():
-        asyncio.run(megacom(args.tty, args.baud, args.mode))
+        asyncio.run(megacom(args.tty, args.baud, args.mode,
+                            args.logfile if args.logfile != "" else None))