diff --git a/Lib/_pyio.py b/Lib/_pyio.py
index e41eb939d1f675b..3186cc83fe3d972 100644
--- a/Lib/_pyio.py
+++ b/Lib/_pyio.py
@@ -1576,7 +1576,7 @@ def __init__(self, file, mode='r', closefd=True, opener=None):
                 # don't exist.
                 pass
             self._blksize = getattr(fdfstat, 'st_blksize', 0)
-            if self._blksize <= DEFAULT_BUFFER_SIZE:
+            if self._blksize < DEFAULT_BUFFER_SIZE:
                 self._blksize = DEFAULT_BUFFER_SIZE
 
             if _setmode: