diff --git a/package.json b/package.json
index eb0949af9..ba204aac6 100644
--- a/package.json
+++ b/package.json
@@ -33,7 +33,7 @@
         "cpx": "^1.5.0",
         "grunt": "1.0.1",
         "grunt-contrib-qunit": "2.0.0",
-        "grunt-contrib-uglify": "3.1.0",
+        "grunt-contrib-uglify": "4.0.1",
         "grunt-ts": "^6.0.0-beta.15",
         "grunt-tslint": "^5.0.2",
         "npm-run-all": "^4.1.3",