diff --git a/Lib/_pyio.py b/Lib/_pyio.py
--- a/Lib/_pyio.py
+++ b/Lib/_pyio.py
@@ -8,12 +8,13 @@
 import errno
 import array
 import stat
+import sys
 # Import _thread instead of threading to reduce startup cost
 try:
     from _thread import allocate_lock as Lock
 except ImportError:
     from _dummy_thread import allocate_lock as Lock
-if os.name == 'win32':
+if sys.platform in {'win32', 'cygwin'}:
     from msvcrt import setmode as _setmode
 else:
     _setmode = None