diff --git a/package-lock.json b/package-lock.json
index 9848576..221d6cd 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -5,9 +5,9 @@
   "requires": true,
   "dependencies": {
     "acorn": {
-      "version": "4.0.3",
-      "resolved": "https://registry.npmjs.org/acorn/-/acorn-4.0.3.tgz",
-      "integrity": "sha1-Gj6FC0KOc7prCdHMUn9aqtTQPvE="
+      "version": "5.7.4",
+      "resolved": "https://registry.npmjs.org/acorn/-/acorn-5.7.4.tgz",
+      "integrity": "sha512-1D++VG7BhrtvQpNbBzovKNc1FLGGEE/oGe7b9xJm/RFHMBeUaUGpluV9RLjZa47YFdPcDAenEYuq9pQPcMdLJg=="
     },
     "acorn-globals": {
       "version": "1.0.9",
diff --git a/package.json b/package.json
index ba438fa..d342906 100644
--- a/package.json
+++ b/package.json
@@ -31,7 +31,7 @@
     "grunt-jade-tasks": "0.0.0"
   },
   "dependencies": {
-    "acorn": "^4.0.3",
+    "acorn": "^5.7.4",
     "clean-css": "^3.4.22",
     "uglify-js": "^2.7.5",
     "with": "^5.1.1"