diff --git a/package.json b/package.json
index 45bd93e..76cae0f 100644
--- a/package.json
+++ b/package.json
@@ -21,6 +21,6 @@
   "devDependencies": {
     "mocha": "*",
     "chai": "*",
-    "rx": "^2.3.11"
+    "rx": "^4.1.0"
   }
 }