diff --git a/Lib/_pyio.py b/Lib/_pyio.py
index 2a1d2a33d02960..7b6d10c008d3cb 100644
--- a/Lib/_pyio.py
+++ b/Lib/_pyio.py
@@ -1806,7 +1806,7 @@ def _isatty_open_only(self):
         """
         if (self._stat_atopen is not None
             and not stat.S_ISCHR(self._stat_atopen.st_mode)):
-            return True
+            return False
         return os.isatty(self._fd)
 
     @property