diff --git a/notes/file.go b/notes/file.go
index 1d9d92a..e27437e 100755
--- a/notes/file.go
+++ b/notes/file.go
@@ -68,7 +68,7 @@ func (n *Notes) commentFormer(urlPath string, md []byte) html.RenderNodeFunc {
 		cur++
 		for cur < len(lines) {
 			for _, opener_closer := range [][]string{{"```", "```"}, {`<summary>`, `</summary>`}} {
-				if bytes.Contains(lines[cur], []byte(opener_closer[0])) {
+				if cur < len(lines) && bytes.Contains(lines[cur], []byte(opener_closer[0])) {
 					cur++
 					for cur < len(lines) && !bytes.Contains(lines[cur], []byte(opener_closer[1])) {
 						cur++