diff --git a/examples/test-cra/.storybook/head.html b/examples/test-cra/.storybook/head.html
new file mode 100644
index 000000000000..3c2df67f7591
--- /dev/null
+++ b/examples/test-cra/.storybook/head.html
@@ -0,0 +1,3 @@
+<script type="text/javascript">
+window.foo = 'bar';
+</script>
diff --git a/examples/test-cra/src/stories/index.js b/examples/test-cra/src/stories/index.js
index 79d7e578671e..19eb55527e35 100644
--- a/examples/test-cra/src/stories/index.js
+++ b/examples/test-cra/src/stories/index.js
@@ -8,6 +8,10 @@ import Button from './Button';
 import Welcome from './Welcome';
 import ComponentWithRef from './ComponentWithRef';
 
+if (window.foo !== 'bar') {
+  throw new Error('`head.html` was not included!');
+}
+
 storiesOf('Welcome', module).add('to Storybook', () => <Welcome showApp={linkTo('Button')} />);
 
 storiesOf('Button', module)