--- lzma.py~	2013-09-09 22:21:08.231447585 -0400
+++ lzma.py	2013-10-08 20:14:01.162225063 -0400
@@ -112,7 +112,7 @@
             self._decompressor = LZMADecompressor(**self._init_args)
             self._buffer = b""
             self._buffer_offset = 0
-        elif mode in ("w", "wb", "a", "ab"):
+        elif mode in ("w", "wb", "a", "ab", "x", "xb"):
             if format is None:
                 format = FORMAT_XZ
             mode_code = _MODE_WRITE