diff --git a/karma.conf.js b/karma.conf.js
index 164cd9ce59..4d699599cb 100644
--- a/karma.conf.js
+++ b/karma.conf.js
@@ -23,6 +23,7 @@ var fs = require('fs');
 //
 var testFile = process.env.KARMA_TEST_FILE || 'test/all-tests.js';
 
+
 process.env.PHANTOMJS_BIN = 'node_modules/.bin/phantomjs';
 
 function fileExists(name) {
@@ -160,10 +161,9 @@ module.exports = function (config) {
 
         webpack: {
             module: {
-                loaders: [
-                    { test: /\.json$/, loader: "json" },
+                rules: [
                     {
-                        test: /\.js$/, loader: "babel",
+                        test: /\.js$/, loader: "babel-loader",
                         include: [path.resolve('./src'),
                                   path.resolve('./test'),
                                  ]
@@ -200,8 +200,9 @@ module.exports = function (config) {
                     'matrix-react-sdk': path.resolve('test/skinned-sdk.js'),
                     'sinon': 'sinon/pkg/sinon.js',
                 },
-                root: [
+                modules: [
                     path.resolve('./test'),
+                    "node_modules"
                 ],
             },
             devtool: 'inline-source-map',
@@ -210,6 +211,8 @@ module.exports = function (config) {
                 // (the 'commonjs' here means it will output a 'require')
                 "electron": "commonjs electron",
             },
+            // make sure we're flagged as development to avoid wasting time optimising
+            mode: 'development',
         },
 
         webpackMiddleware: {
diff --git a/package.json b/package.json
index dbb034c593..370ed541dd 100644
--- a/package.json
+++ b/package.json
@@ -53,7 +53,7 @@
     "test-multi": "karma start"
   },
   "dependencies": {
-    "babel-runtime": "^6.11.6",
+    "babel-runtime": "^6.26.0",
     "bluebird": "^3.5.0",
     "blueimp-canvas-to-blob": "^3.5.0",
     "browser-encrypt-attachment": "^0.3.0",
@@ -98,41 +98,40 @@
     "whatwg-fetch": "^1.1.1"
   },
   "devDependencies": {
-    "babel-cli": "^6.5.2",
-    "babel-core": "^6.14.0",
+    "babel-cli": "^6.26.0",
+    "babel-core": "^6.26.3",
     "babel-eslint": "^6.1.2",
-    "babel-loader": "^6.2.5",
+    "babel-loader": "^7.1.5",
     "babel-plugin-add-module-exports": "^0.2.1",
     "babel-plugin-transform-async-to-bluebird": "^1.1.1",
-    "babel-plugin-transform-class-properties": "^6.16.0",
-    "babel-plugin-transform-object-rest-spread": "^6.16.0",
-    "babel-plugin-transform-runtime": "^6.15.0",
-    "babel-polyfill": "^6.5.0",
-    "babel-preset-es2015": "^6.14.0",
-    "babel-preset-es2016": "^6.11.3",
-    "babel-preset-es2017": "^6.14.0",
-    "babel-preset-react": "^6.11.1",
+    "babel-plugin-transform-class-properties": "^6.24.1",
+    "babel-plugin-transform-object-rest-spread": "^6.26.0",
+    "babel-plugin-transform-runtime": "^6.23.0",
+    "babel-polyfill": "^6.26.0",
+    "babel-preset-es2015": "^6.24.1",
+    "babel-preset-es2016": "^6.24.1",
+    "babel-preset-es2017": "^6.24.1",
+    "babel-preset-react": "^6.24.1",
     "chokidar": "^1.6.1",
     "concurrently": "^4.0.1",
     "eslint": "^3.13.1",
     "eslint-config-google": "^0.7.1",
-    "eslint-plugin-babel": "^4.0.1",
+    "eslint-plugin-babel": "^4.1.2",
     "eslint-plugin-flowtype": "^2.30.0",
     "eslint-plugin-react": "^7.7.0",
     "estree-walker": "^0.5.0",
     "expect": "^1.16.0",
     "flow-parser": "^0.57.3",
-    "json-loader": "^0.5.3",
     "karma": "^3.0.0",
     "karma-chrome-launcher": "^0.2.3",
-    "karma-cli": "^0.1.2",
-    "karma-junit-reporter": "^1.2.0",
+    "karma-cli": "^1.0.1",
+    "karma-junit-reporter": "^0.4.2",
     "karma-logcapture-reporter": "0.0.1",
-    "karma-mocha": "^0.2.2",
+    "karma-mocha": "^1.3.0",
     "karma-sourcemap-loader": "^0.3.7",
     "karma-spec-reporter": "^0.0.31",
-    "karma-summary-reporter": "^1.3.3",
-    "karma-webpack": "^3.0.5",
+    "karma-summary-reporter": "^1.5.1",
+    "karma-webpack": "^4.0.0-beta.0",
     "matrix-mock-request": "^1.2.1",
     "matrix-react-test-utils": "^0.1.1",
     "mocha": "^5.0.5",
@@ -142,6 +141,7 @@
     "sinon": "^5.0.7",
     "source-map-loader": "^0.2.3",
     "walk": "^2.3.9",
-    "webpack": "^1.12.14"
+    "webpack": "^4.20.2",
+    "webpack-cli": "^3.1.1"
   }
 }