diff --git a/code/02-Router4/package.json b/code/02-Router4/package.json
index 1542af9..c45b003 100644
--- a/code/02-Router4/package.json
+++ b/code/02-Router4/package.json
@@ -43,7 +43,7 @@
     "sw-precache-webpack-plugin": "0.11.4",
     "url-loader": "0.5.9",
     "webpack": "3.5.1",
-    "webpack-dev-server": "2.8.2",
+    "webpack-dev-server": "3.11.0",
     "webpack-manifest-plugin": "1.2.1",
     "whatwg-fetch": "2.0.3"
   },