diff --git a/02-preprocess/package-lock.json b/02-preprocess/package-lock.json
index b837919..5448cb2 100644
--- a/02-preprocess/package-lock.json
+++ b/02-preprocess/package-lock.json
@@ -67,9 +67,9 @@
       }
     },
     "acorn": {
-      "version": "6.2.0",
-      "resolved": "https://registry.npmjs.org/acorn/-/acorn-6.2.0.tgz",
-      "integrity": "sha512-8oe72N3WPMjA+2zVG71Ia0nXZ8DpQH+QyyHO+p06jT8eg8FGG3FbcUIi8KziHlAfheJQZeoqbvq1mQSQHXKYLw==",
+      "version": "6.4.2",
+      "resolved": "https://registry.npmjs.org/acorn/-/acorn-6.4.2.tgz",
+      "integrity": "sha512-XtGIhXwF8YM8bJhGxG5kXgjkEuNGLTkoYqVE+KMR+aspr4KGYmKYg7yUe3KghyQ9yheNwLnjmzh/7+gfDBmHCQ==",
       "dev": true
     },
     "acorn-walk": {