diff --git a/.circleci/config.yml b/.circleci/config.yml
index 1904dd3c..45842de4 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -1,23 +1,31 @@
-defaults: &defaults
+checkout_submodule: &checkout_submodule
+  run:
+    name: Checkout submodule
+    command: |
+        git submodule sync
+        git submodule update --init --recursive
+
+npm_cache_key: &npm_cache_key
+  npm-deps-v1-{{ checksum "package.json" }}
+
+restore_npm_cache: &restore_npm_cache
+  restore_cache:
+    keys:
+      - *npm_cache_key
+      - npm-deps-v1-
+
+npm_install: &npm_install
+  run:
+    name: Install npm dependencies
+    command: npm install
+
+screenshotter: &screenshotter
   steps:
     - checkout
-    - run:
-        name: Checkout submodule
-        command: |
-            git submodule sync
-            git submodule update --init --recursive
+    - *checkout_submodule
 
-    - restore_cache:
-        keys:
-          - npm-deps-{{ checksum "package.json" }}
-          - npm-deps-
-    - run:
-        name: Install npm dependencies
-        command: npm install
-    - save_cache:
-        key: npm-deps-{{ checksum "package.json" }}
-        paths:
-          - node_modules
+    - *restore_npm_cache
+    - *npm_install
 
     - run:
         name: Verify screenshots and generate diffs and new screenshots
@@ -32,20 +40,66 @@ defaults: &defaults
 
 version: 2
 jobs:
+  test:
+    docker:
+      - image: circleci/node:6
+    steps:
+      - run:
+          name: Check whether the build is running on the main repository
+          command: |
+              if [[ $CIRCLE_PULL_REQUEST && $CIRCLE_PROJECT_USERNAME != "Khan" ]]; then
+                echo "Please disable CircleCI on your forked repository!"
+                exit 1
+              fi
+
+      - checkout
+      - *checkout_submodule
+
+      - *restore_npm_cache
+      - *npm_install
+      - save_cache:
+          key: *npm_cache_key
+          paths:
+            - node_modules
+
+      - run:
+          name: Run tests
+          command: npm test -- -- --coverage
+      - run:
+          name: Install codecov and upload results
+          command: |
+              sudo npm install -g codecov
+              codecov
+
+      - run:
+          name: Build KaTeX
+          command: npm run build
+
+      - store_artifacts:
+          path: dist/katex.js
+          destination: katex.js
+      - store_artifacts:
+          path: dist/katex.css
+          destination: katex.css
+      - store_artifacts:
+          path: dist/fonts
+          destination: fonts
+
   firefox:
     docker:
       - image: circleci/node:6
       - image: selenium/standalone-firefox:2.48.2
-    <<: *defaults
+    <<: *screenshotter
   chrome:
     docker:
       - image: circleci/node:6
       - image: selenium/standalone-chrome:2.48.2
-    <<: *defaults
+    <<: *screenshotter
 
 workflows:
   version: 2
   screenshotter:
     jobs:
+      - test
       - firefox
       - chrome
diff --git a/README.md b/README.md
index 62e5571e..c8bed79f 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,6 @@
 # [<img src="https://khan.github.io/KaTeX/katex-logo.svg" width="130" alt="KaTeX">](https://khan.github.io/KaTeX/)
 [![Build Status](https://travis-ci.org/Khan/KaTeX.svg?branch=master)](https://travis-ci.org/Khan/KaTeX)
+[![CircleCI](https://circleci.com/gh/Khan/KaTeX.svg?style=svg)](https://circleci.com/gh/Khan/KaTeX)
 [![codecov](https://codecov.io/gh/Khan/KaTeX/branch/master/graph/badge.svg)](https://codecov.io/gh/Khan/KaTeX)
 [![Join the chat at https://gitter.im/Khan/KaTeX](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/Khan/KaTeX?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) [![Greenkeeper badge](https://badges.greenkeeper.io/Khan/KaTeX.svg)](https://greenkeeper.io/)
 ![](https://img.badgesize.io/Khan/KaTeX/v0.10.0-beta/dist/katex.min.js?compression=gzip)
diff --git a/dockers/Screenshotter/README.md b/dockers/Screenshotter/README.md
index fa724d9d..43d4ac68 100644
--- a/dockers/Screenshotter/README.md
+++ b/dockers/Screenshotter/README.md
@@ -48,10 +48,9 @@ fashion are well suited for visual inspection, but for exact binary
 comparisons it would be neccessary to carefully set up the environment
 to match the one used by the Docker approach.
 
-You can also verify and generate screenshots online using a CI(continuous
-integration) service. Fork the project, enable [CircleCI](https://circleci.com/) on your repository,
-and push your changes. Diffs and generated screenshots are available at
-build artifacts.
+Screenshots can also be verified and generated by opening a pull request.
+Diffs and generated screenshots are available at the `Artifacts` section
+of CircleCI builds.
 
 ## Choosing the list of test cases
 
diff --git a/dockers/Screenshotter/screenshotter.js b/dockers/Screenshotter/screenshotter.js
index cbad6438..10df40ee 100644
--- a/dockers/Screenshotter/screenshotter.js
+++ b/dockers/Screenshotter/screenshotter.js
@@ -14,7 +14,7 @@ const firefox = require("selenium-webdriver/firefox");
 
 const webpack = require('webpack');
 const webpackDevServer = require("webpack-dev-server");
-const webpackConfig = require("../../webpack.dev");
+const webpackConfig = require("../../webpack.dev")[0];
 const data = require("../../test/screenshotter/ss_data");
 
 // Change to KaTeX root directory so that webpack (in particular
@@ -162,7 +162,7 @@ function startServer() {
     }
     const port = Math.floor(Math.random() * (maxPort - minPort)) + minPort;
     const compiler = webpack(webpackConfig);
-    const wds = new webpackDevServer(compiler, webpackConfig[0].devServer);
+    const wds = new webpackDevServer(compiler, webpackConfig.devServer);
     const server = wds.listen(port);
     server.once("listening", function() {
         devServer = wds;