diff --git a/sort/4.shellSort.md b/sort/4.shellSort.md
index cfa59f58..e1e99a3d 100644
--- a/sort/4.shellSort.md
+++ b/sort/4.shellSort.md
@@ -69,7 +69,7 @@ def shellSort(arr):
 func shellSort(arr []int) []int {
 	length := len(arr)
 	gap := 1
-	for gap < gap/3 { + for gap < length/3 { gap = gap*3 + 1 } for gap> 0 {
</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://patch-diff.githubusercontent.com/raw/geekxh/hello-algorithm/pull/1.diff">(-&gt;オリジナル)</a>
/ <label>アドレス: <input type="text" name="naked_post_url" value="https://patch-diff.githubusercontent.com/raw/geekxh/hello-algorithm/pull/1.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">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>
</form>
</div>