diff --git a/package.json b/package.json
index 6c5f244..f1f07f5 100644
--- a/package.json
+++ b/package.json
@@ -12,7 +12,7 @@
   "license": "MIT",
   "dependencies": {
     "express": "^4.13.4",
-    "mobx": "^3.2.1",
+    "mobx": "^4.1.1",
     "mobx-react": "^4.2.2",
     "react": "^15.6.1",
     "react-dom": "^15.6.1",