diff --git a/Lib/importlib/_bootstrap.py b/Lib/importlib/_bootstrap.py
--- a/Lib/importlib/_bootstrap.py
+++ b/Lib/importlib/_bootstrap.py
@@ -142,7 +142,9 @@
 
 
 def _write_atomic(path, data):
- """Function to write data to a path atomically."""
+ """Best-effort function to write data to a path atomically.
+ Be prepared to handle a FileExistsError if concurrent writing of the
+ temporary file is attempted."""
 # id() is used to generate a pseudo-random filename.
 path_tmp = '{}.{}'.format(path, id(path))
 fd = _os.open(path_tmp, _os.O_EXCL | _os.O_CREAT | _os.O_WRONLY, 0o666)
@@ -597,8 +599,9 @@
 return
 try:
 _write_atomic(path, data)
- except PermissionError:
- # Don't worry if you can't write bytecode.
+ except (PermissionError, FileExistsError):
+ # Don't worry if you can't write bytecode or someone is writing
+ # it at the same time.
 pass
 
 
</div><div class="naked_ctrl">
<form action="/index.cgi/contrast" method="get" name="gate">
<p><a href="http://altstyle.alfasado.net">AltStyle</a> によって変換されたページ <a href="https://bugs.python.org/file24593/atomic_exists.diff">(-&gt;オリジナル)</a>
/ <label>アドレス: <input type="text" name="naked_post_url" value="https://bugs.python.org/file24593/atomic_exists.diff" size="22" /></label> <label>モード: <select name="naked_post_mode">
<option value="default">デフォルト</option>
<option value="speech">音声ブラウザ</option>
<option value="ruby">ルビ付き</option>
<option value="contrast" selected="selected">配色反転</option>
<option value="larger-text">文字拡大</option>
<option value="mobile">モバイル</option>
</select>
<input type="submit" value="表示" />
</p>
</form>
</div>