diff --git a/package.json b/package.json
index 7f30dc1..343e203 100644
--- a/package.json
+++ b/package.json
@@ -61,7 +61,7 @@
     "merge-stream": "^1.0.1",
     "nyc": "^11.7.3",
     "rollup": "^0.59.0",
-    "rollup-plugin-uglify": "^3.0.0",
+    "rollup-plugin-uglify": "^4.0.0",
     "run-sequence": "^2.2.1",
     "tslint": "^5.10.0",
     "typedoc": "^0.11.1",