diff --git a/src/mcp/server/stdio.py b/src/mcp/server/stdio.py
index 5c1459dff..9bf91160a 100644
--- a/src/mcp/server/stdio.py
+++ b/src/mcp/server/stdio.py
@@ -17,6 +17,7 @@ async def run_server():
     ```
 """
 
+import os
 import sys
 from contextlib import asynccontextmanager
 from io import TextIOWrapper
@@ -38,10 +39,16 @@ async def stdio_server(stdin: anyio.AsyncFile[str] | None = None, stdout: anyio.
     # standard process handles. Encoding of stdin/stdout as text streams on
     # python is platform-dependent (Windows is particularly problematic), so we
     # re-wrap the underlying binary stream to ensure UTF-8.
+    # We duplicate the file descriptors to avoid closing the original stdio
+    # when the transport is closed (fixes issue #1933).
     if not stdin:
-        stdin = anyio.wrap_file(TextIOWrapper(sys.stdin.buffer, encoding="utf-8", errors="replace"))
+        stdin_fd = os.dup(sys.stdin.fileno())
+        stdin_bin = os.fdopen(stdin_fd, "rb", closefd=True)
+        stdin = anyio.wrap_file(TextIOWrapper(stdin_bin, encoding="utf-8", errors="replace"))
     if not stdout:
-        stdout = anyio.wrap_file(TextIOWrapper(sys.stdout.buffer, encoding="utf-8"))
+        stdout_fd = os.dup(sys.stdout.fileno())
+        stdout_bin = os.fdopen(stdout_fd, "wb", closefd=True)
+        stdout = anyio.wrap_file(TextIOWrapper(stdout_bin, encoding="utf-8"))
 
     read_stream_writer, read_stream = create_context_streams[SessionMessage | Exception](0)
     write_stream, write_stream_reader = create_context_streams[SessionMessage](0)