diff --git a/package.json b/package.json
index 415089cc..d2416bda 100644
--- a/package.json
+++ b/package.json
@@ -15,7 +15,8 @@
     "extract-zip": "^1.6.5",
     "mime": "^1.3.4",
     "progress": "^2.0.0",
-    "rimraf": "^2.6.1"
+    "rimraf": "^2.6.1",
+    "ws": "^3.0.0"
   },
   "puppeteer": {
     "chromium_revision": "478524"