diff --git a/package.json b/package.json
index 4821bff..920775f 100644
--- a/package.json
+++ b/package.json
@@ -40,7 +40,7 @@
     "istanbul": "*",
     "mocha": "*",
     "mochify": "^2.9.0",
-    "uglify-js": "1.3.x"
+    "uglify-js": "3.6.x"
   },
   "main": "lib/string",
   "scripts": {