diff --git a/karma.conf.js b/karma.conf.js
index eed6d580fa..0abbddb71b 100644
--- a/karma.conf.js
+++ b/karma.conf.js
@@ -11,11 +11,18 @@ var fs = require('fs');
  * If you run karma in multi-run mode (with `npm run test-multi`), it will watch
  * the tests for changes, and webpack will rebuild using a cache. This is much quicker
  * than a clean rebuild.
- *
- * TODO:
- * - can we run one test at a time?
  */
 
+// the name of the test file. By default, a special file which runs all tests.
+//
+// TODO: this could be a pattern, and karma would run each file, with a
+// separate webpack bundle for each file. But then we get a separate instance
+// of the sdk, and each of the dependencies, for each test file, and everything
+// gets very confused. Can we persuade webpack to put all of the dependencies
+// in a 'common' bundle?
+//
+var testFile = process.env.KARMA_TEST_FILE || 'test/all-tests.js';
+
 process.env.PHANTOMJS_BIN = 'node_modules/.bin/phantomjs';
 
 function fileExists(name) {
@@ -33,6 +40,7 @@ if (!fileExists(gsCss)) {
     gsCss = 'node_modules/react-gemini-scrollbar/'+gsCss;
 }
 
+
 module.exports = function (config) {
     config.set({
         // frameworks to use
@@ -41,15 +49,15 @@ module.exports = function (config) {
 
         // list of files / patterns to load in the browser
         files: [
-            'test/tests.js',
+            testFile,
             gsCss,
         ],
 
         // list of files to exclude
         //
         // This doesn't work. It turns out that it's webpack which does the
-        // watching of the /test directory (possibly karma only watches
-        // tests.js itself). Webpack watches the directory so that it can spot
+        // watching of the /test directory (karma only watches `testFile`
+        // itself). Webpack watches the directory so that it can spot
         // new tests, which is fair enough; unfortunately it triggers a rebuild
         // every time a lockfile is created in that directory, and there
         // doesn't seem to be any way to tell webpack to ignore particular
@@ -63,7 +71,7 @@ module.exports = function (config) {
         // available preprocessors:
         // https://npmjs.org/browse/keyword/karma-preprocessor
         preprocessors: {
-            'test/tests.js': ['webpack', 'sourcemap']
+            'test/**/*.js': ['webpack', 'sourcemap']
         },
 
         // test results reporter to use
@@ -139,7 +147,7 @@ module.exports = function (config) {
             },
             resolve: {
                 alias: {
-                    'matrix-react-sdk': path.resolve('src/index.js'),
+                    'matrix-react-sdk': path.resolve('test/skinned-sdk.js'),
                     'sinon': 'sinon/pkg/sinon.js',
                 },
                 root: [
diff --git a/test/tests.js b/test/all-tests.js
similarity index 53%
rename from test/tests.js
rename to test/all-tests.js
index 3eec9ae8ee..6e604f84ad 100644
--- a/test/tests.js
+++ b/test/all-tests.js
@@ -1,11 +1,7 @@
-// tests.js
+// all-tests.js
 //
 // Our master test file: uses the webpack require API to find our test files
 // and run them
 
-// this is a handly place to make sure the sdk has been skinned
-var sdk = require("matrix-react-sdk");
-sdk.loadSkin(require('./test-component-index'));
-
 var context = require.context('.', true, /-test\.jsx?$/);
 context.keys().forEach(context);
diff --git a/test/test-component-index.js b/test/skinned-sdk.js
similarity index 74%
rename from test/test-component-index.js
rename to test/skinned-sdk.js
index 0ab5f693dd..5d3526b797 100644
--- a/test/test-component-index.js
+++ b/test/skinned-sdk.js
@@ -1,12 +1,16 @@
 /*
- * test-component-index.js
+ * skinned-sdk.js
  *
- * Stub out a bunch of the components which we expect the application to
- * provide
+ * Skins the react-sdk with a few stub components which we expect the
+ * application to provide
  */
-var components = require('../src/component-index.js').components;
+
+var sdk = require("../src/index");
+
+var skin = require('../src/component-index.js');
 var stubComponent = require('./components/stub-component.js');
 
+var components = skin.components;
 components['structures.LeftPanel'] = stubComponent();
 components['structures.RightPanel'] = stubComponent();
 components['structures.RoomDirectory'] = stubComponent();
@@ -18,4 +22,6 @@ components['views.messages.DateSeparator'] = stubComponent({displayName: 'DateSe
 components['views.messages.MessageTimestamp'] = stubComponent({displayName: 'MessageTimestamp'});
 components['views.messages.SenderProfile'] = stubComponent({displayName: 'SenderProfile'});
 
-module.exports.components = components;
+sdk.loadSkin(skin);
+
+module.exports = sdk;