diff --git a/package.json b/package.json
index 52c8d9096..3ed7a49f4 100644
--- a/package.json
+++ b/package.json
@@ -14,6 +14,7 @@
     "browserify": "^13.0.0",
     "browserify-shim": "^3.8.12",
     "cssnano": "^3.5.2",
+    "es6-promise": "^3.2.1",
     "grunt": ">=0.4.0",
     "grunt-browserify": "^5.0.0",
     "grunt-cli": "^1.2.0",
@@ -33,7 +34,8 @@
     "pickadate": "^3.5.6",
     "pixrem": "^3.0.0",
     "postcss-cssnext": "^2.5.1",
-    "prismjs": "^1.4.1"
+    "prismjs": "^1.4.1",
+    "through": "^2.3.8"
   },
   "engines": {
     "node": ">0.12"