diff --git a/main.ts b/main.ts
index 587f996..eb8a228 100644
--- a/main.ts
+++ b/main.ts
@@ -19,7 +19,7 @@ export default class PAUL extends Plugin {
 		if (activeFile && activeFile.extension === 'md') {
 			this.app.vault.read(activeFile).then(content => {
 				const pattern = /Modified: \d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}Z/;
-				let digit = (inp)=>{ return String(inp).padStart(2, '0') }
+				const digit = (inp: number)=>{ return String(inp).padStart(2, '0') }
 				const t = new Date()
 				const modified = `Modified: ${t.getFullYear()}-${digit(t.getMonth()+1)}-${digit(t.getDate())}T${digit(t.getHours())}:${digit(t.getMinutes())}:${digit(t.getSeconds())}Z`;
 
@@ -32,6 +32,10 @@ export default class PAUL extends Plugin {
 					const analysis = content.match(/^---\n((?!-{3})(?:(?:.+:.*)|(?:\s{2}-\s.+))\n)+---/);
 					// const analysis = content.match(/---\n(.*:.*\n)*---/s);
 					// console.log(analysis);
+					// frontmatter가 없으면 삽입할 위치를 찾을 수 없으므로 중단
+					if (!analysis || analysis.index === undefined) {
+						return;
+					}
 					const pnt = analysis.index + analysis[0].length - 3;
 					this.app.vault.modify(activeFile, content.slice(0, pnt) + modified + '\n' + content.slice(pnt));
 				}
diff --git a/package.json b/package.json
index 6a00766..1808666 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
-	"name": "obsidian-sample-plugin",
-	"version": "1.0.0",
+	"name": "obsidian-modified-time-updater",
+	"version": "1.1.0",
 	"description": "This is a sample plugin for Obsidian (https://obsidian.md)",
 	"main": "main.js",
 	"scripts": {
diff --git a/tsconfig.json b/tsconfig.json
index 2d6fbdf..d7c8e6a 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -15,7 +15,8 @@
       "DOM",
       "ES5",
       "ES6",
-      "ES7"
+      "ES7",
+      "ES2017"
     ]
   },
   "include": [