diff --git a/packages/md-aggregate/cli.mjs b/packages/md-aggregate/cli.mjs
index 43d2c2de..192c2d96 100644
--- a/packages/md-aggregate/cli.mjs
+++ b/packages/md-aggregate/cli.mjs
@@ -1,5 +1,6 @@
 #!/usr/bin/env node
 import arg from "arg";
+import escapeStringRegexp from "escape-string-regexp";
 import { readFile, writeFile } from "fs/promises";
 import { parse, resolve } from "path";
 
@@ -47,9 +48,8 @@ export const cli = async (rawArgv) => {
       .split("\n")
       .map((e) => e.replace(/^#/g, "##"));
 
-    // TODO: escape regexp startPattern
     // TODO: handle \r\n
-    const matchStartPattern = `\n${lines[0]}$`;
+    const matchStartPattern = `\n${escapeStringRegexp(lines[0])}$`;
     const eofPattern = "$(?![\\r\\n])";
 
     const sectionStartPattern = `\n##? `;
@@ -67,7 +67,7 @@ export const cli = async (rawArgv) => {
   if (!args["--write"]) return console.log(dstContent);
 
   await writeFile(resolve(dst), dstContent);
-  
+
   console.log(resolve(dst));
 };
 
diff --git a/packages/md-aggregate/package.json b/packages/md-aggregate/package.json
index 8d769ae1..666107e9 100644
--- a/packages/md-aggregate/package.json
+++ b/packages/md-aggregate/package.json
@@ -9,7 +9,8 @@
     "prepack": "prettier -w CHANGELOG.md && md-aggregate CHANGELOG.md README.md -w"
   },
   "dependencies": {
-    "arg": "^5.0.1"
+    "arg": "^5.0.1",
+    "escape-string-regexp": "^5.0.0"
   },
   "publishConfig": {
     "access": "public"
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 26f6b71f..10651996 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -52,8 +52,10 @@ importers:
   packages/md-aggregate:
     specifiers:
       arg: ^5.0.1
+      escape-string-regexp: ^5.0.0
     dependencies:
       arg: 5.0.1
+      escape-string-regexp: 5.0.0
 
   packages/sno-mongo-ku:
     specifiers:
@@ -4080,6 +4082,11 @@ packages:
     engines: {node: '>=10'}
     dev: true
 
+  /escape-string-regexp/5.0.0:
+    resolution: {integrity: sha512-/veY75JbMK4j1yjvuUxuVsiS/hr/4iHs9FTT6cgTexxdE0Ly/glccBAkloH/DofkjRbZU3bnoj38mOmhkZ0lHw==}
+    engines: {node: '>=12'}
+    dev: false
+
   /eslint-config-airbnb-base/15.0.0_6e04a54c7bcd7530b1a4c2da0aa486b1:
     resolution: {integrity: sha512-xaX3z4ZZIcFLvh2oUNvcX5oEofXda7giYmuplVxoOg5A7EXJMrUyqRgR+mhDhPK8LZ4PttFOBvCYDbX3sUoUig==}
     engines: {node: ^10.12.0 || >=12.0.0}