diff --git a/package.json b/package.json
index e1fcfe6de5..181995903e 100644
--- a/package.json
+++ b/package.json
@@ -47,6 +47,7 @@
     "cross-env": "^5.2.0",
     "css": "^2.2.4",
     "events": "^3.0.0",
+    "eventsource": "^1.0.7",
     "fake-indexeddb": "^2.0.4",
     "find": "^0.2.9",
     "he": "^1.1.1",