diff --git a/codegenerator/rust_cli.py b/codegenerator/rust_cli.py
index b4d5f91..cd637d8 100644
--- a/codegenerator/rust_cli.py
+++ b/codegenerator/rust_cli.py
@@ -1102,7 +1102,9 @@ class RustCliGenerator(BaseGenerator):
 context = {
 "operation_id": operation_id,
 "operation_type": args.operation_type,
- "operation_name": args.operation_name,
+ "operation_name": (
+ args.operation_name or args.operation_type
+ ).lower(),
 "command_description": common_rust.sanitize_rust_docstrings(
 command_description
 ),
</div><div class="naked_ctrl">
<form action="/index.cgi/larger-text" 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://opendev.org/openstack/codegenerator/commit/9872d0f5901ae4d8f52fd8fa3ffbe01ae95bd889.diff">(-&gt;オリジナル)</a>
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<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">配色反転</option>
<option value="larger-text" selected="selected">文字拡大</option>
<option value="mobile">モバイル</option>
</select>
<input type="submit" value="表示" />
</p>
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</div>