diff --git a/src/provider.tsx b/src/provider.tsx
index 2dc1fa15..91b12a2b 100644
--- a/src/provider.tsx
+++ b/src/provider.tsx
@@ -30,7 +30,7 @@ export const UpdateProvider = ({
 client = useRef(client).current;
 const { options } = client;
 
- const stateListener = useRef<nativeeventsubscription>();
+ const stateListener = useRef<nativeeventsubscription&#124;null>(null);
 const [updateInfo, setUpdateInfo] = useState<checkresult>();
 const updateInfoRef = useRef(updateInfo);
 const [progress, setProgress] = useState<progressdata>();
</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://github.com/reactnativecn/react-native-update/compare/master...Suo-Ran:react-native-update:master.diff">(-&gt;オリジナル)</a>
/ <label>アドレス: <input type="text" name="naked_post_url" value="https://github.com/reactnativecn/react-native-update/compare/master...Suo-Ran:react-native-update:master.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>