cmaloney
diff --git a/‎Lib/_pyio.py
Lines changed: 2 additions & 4 deletions b/‎Lib/_pyio.py
Lines changed: 2 additions & 4 deletions
@@ -937,10 +937,8 @@ def write(self, b):
             return 0
         pos = self._pos
         if pos > len(self._buffer):
-            # Inserts null bytes between the current end of the file
-            # and the new write position.
-            padding = b'\x00' * (pos - len(self._buffer))
-            self._buffer += padding
+            # Expand the buffer to be able to hold the new bytes.
+            self._buffer.resize(pos + n)
         self._buffer[pos:pos + n] = b
         self._pos += n
         return n