diff --git a/package.json b/package.json
index f0b6628d..e0d14742 100644
--- a/package.json
+++ b/package.json
@@ -41,6 +41,7 @@
     "mocha-circleci-reporter": "0.0.1",
     "should": "^8.0.1",
     "style-loader": "^0.13.0",
+    "through2": "^2.0.1",
     "vinyl-named": "^1.1.0",
     "webdriverio": "^3.3.0",
     "webpack-stream": "^3.1.0"