diff --git a/packages/react-scripts/package.json b/packages/react-scripts/package.json
index 3b31c7393..d5c599e55 100644
--- a/packages/react-scripts/package.json
+++ b/packages/react-scripts/package.json
@@ -40,7 +40,7 @@
     "raf": "3.4.0",
     "react-dev-utils": "4.2.1",
     "sass-loader": "^6.0.6",
-    "source-map-loader": "^0.2.1",
+    "source-map-loader": "^1.0.0",
     "style-loader": "0.19.0",
     "sw-precache-webpack-plugin": "0.11.4",
     "ts-jest": "^20.0.7",
@@ -49,7 +49,7 @@
     "tslint": "^5.7.0",
     "tslint-react": "^3.2.0",
     "url-loader": "0.6.2",
-    "webpack": "3.8.1",
+    "webpack": "4.0.0",
     "webpack-dev-server": "2.9.4",
     "webpack-manifest-plugin": "1.3.2",
     "whatwg-fetch": "2.0.3"