diff --git a/.eslintrc.js b/.eslintrc.js
index ccd7e61..ba7f639 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -1,5 +1,10 @@
 /* @flow */
 
 module.exports = {
-    'extends': './node_modules/grumbler-scripts/config/.eslintrc-node.js'
-};
\ No newline at end of file
+    'extends': './node_modules/grumbler-scripts/config/.eslintrc-node.js',
+    'rules': {
+      // legacy rule settings
+      'prefer-const': 'off',
+      'flowtype/require-exact-type': 'off'
+    }
+};
diff --git a/.flowconfig b/.flowconfig
index 50394de..28da5d2 100644
--- a/.flowconfig
+++ b/.flowconfig
@@ -1,5 +1,5 @@
 [ignore]
-.*/node_modules/babel-plugin-flow-runtime
+.*/node_modules/@babel
 .*/node_modules/npm
 .*/node_modules/resolve
 [include]
diff --git a/.npmrc b/.npmrc
index ea171c4..69c1a8d 100644
--- a/.npmrc
+++ b/.npmrc
@@ -1,3 +1,3 @@
-registry=http://registry.npmjs.com/
+registry=https://registry.npmjs.org/
 package-lock=false
 save=false
diff --git a/.babelrc b/babel.config.json
similarity index 100%
rename from .babelrc
rename to babel.config.json
diff --git a/package.json b/package.json
index 65a75d8..3124bbe 100644
--- a/package.json
+++ b/package.json
@@ -7,7 +7,7 @@
   "scripts": {
     "flow-typed": "flow-typed install",
     "flow:build": "flow gen-flow-files ./src/index.js --out-dir ./src",
-    "babel": "babel src/*.js src/**/*.js --exclude=node_modules --out-dir . --source-maps inline",
+    "babel": "babel ./src --ignore=node_modules --out-dir ./src --source-maps inline",
     "test": "npm run flow-typed && npm run lint && npm run flow && npm run tsd",
     "tsd": "tsd",
     "flow": "flow",
@@ -33,7 +33,7 @@
   "devDependencies": {
     "@types/express": "^4.17.13",
     "flow-bin": "^0.69.0",
-    "grumbler-scripts": "^2.0.7",
+    "grumbler-scripts": "^5.0.0",
     "in-publish": "^2.0.1",
     "tsd": "^0.19.1",
     "yargs-parser": "^10.0.0"
diff --git a/src/express.js b/src/express.js
index cd6feb7..c15a0ce 100644
--- a/src/express.js
+++ b/src/express.js
@@ -2,7 +2,7 @@
 
 import https from 'https';
 
-import express from 'express'; // eslint-disable-line import/no-unresolved
+import express from 'express';
 
 type ExpressRequest = express$Request; // eslint-disable-line no-undef
 type ExpressResponse = express$Response; // eslint-disable-line no-undef