diff --git a/package.json b/package.json
index 5c521ab..1bce51e 100644
--- a/package.json
+++ b/package.json
@@ -34,6 +34,6 @@
     "hifive-tap": "~0.1.0",
     "hifive": "~0.1.0",
     "deep-equal": "~0.1.0",
-    "uglify-js": "~2.4.3"
+    "uglify-js": "~3.6.8"
   }
 }