diff --git a/src/app/content/components/ContentWarning.spec.tsx b/src/app/content/components/ContentWarning.spec.tsx
index edb93b435e..57889aec04 100644
--- a/src/app/content/components/ContentWarning.spec.tsx
+++ b/src/app/content/components/ContentWarning.spec.tsx
@@ -1,28 +1,74 @@
-import React from 'react';
-import { renderToDom } from '../../../test/reactutils';
-import ContentWarning from './ContentWarning';
-import { act } from 'react-dom/test-utils';
-import ReactTestUtils from 'react-dom/test-utils';
 import { book as archiveBook } from '../../../test/mocks/archiveLoader';
+import type rendererType from 'react-test-renderer';
+import type { ComponentType } from 'react';
 import { mockCmsBook } from '../../../test/mocks/osWebLoader';
+import { reactAndFriends, resetModules } from '../../../test/utils';
 import { formatBookData } from '../utils';
 
+
 const dummyBook = {
   ...formatBookData(archiveBook, mockCmsBook),
   content_warning_text: 'some warning text',
 };
 
 describe('ContentWarning', () => {
-  it('renders warning modal', async() => {
-    renderToDom(<ContentWarning book={dummyBook} />);
+  let React: ReturnType<typeof reactAndFriends>['React']; // tslint:disable-line:variable-name
+  let ContentWarningDynamic: ComponentType<any>; // tslint:disable-line:variable-name
+
+  describe('in browser', () => {
+    let renderToDom: ReturnType<typeof reactAndFriends>['renderToDom'];
+    let ReactDOMTestUtils: ReturnType<typeof reactAndFriends>['ReactDOMTestUtils']; // tslint:disable-line:variable-name
+
+    beforeEach(() => {
+      resetModules();
+      jest.doMock('react', () => {
+        const react = (jest as any).requireActual('react');
+        return { ...react, useEffect: react.useLayoutEffect };
+      });
+
+      ({React, renderToDom, ReactDOMTestUtils} = reactAndFriends());
+
+      ContentWarningDynamic = require('./ContentWarning').default;
+    });
+
+    it('renders warning modal and hides it after clicking', async() => {
+      renderToDom(<ContentWarningDynamic book={dummyBook} />);
+
+      const b = document!.querySelector('button');
+
+      expect(b).toBeTruthy();
+      // Exercises the when-focus-is-already-in-the-modal branch
+      b!.focus();
+
+      ReactDOMTestUtils.act(() => ReactDOMTestUtils.Simulate.click(b!));
+
+      expect(document!.querySelector('button')).toBeFalsy();
+    });
+  });
+
+  describe('outside the browser', () => {
+    const windowBackup = window;
+    const documentBackup = document;
+
+    let renderer: typeof rendererType;
+
+    beforeEach(() => {
+      delete (global as any).window;
+      delete (global as any).document;
+      resetModules();
+      ({React, renderer} = reactAndFriends());
+
+      ContentWarningDynamic = require('./ContentWarning').default;
+    });
 
-    const root = document?.body;
-    const b = root?.querySelector('button');
+    afterEach(() => {
+      (global as any).window = windowBackup;
+      (global as any).document = documentBackup;
+    });
 
-    expect(b).toBeTruthy();
-    // Exercises the when-focus-is-already-in-the-modal branch
-    b!.focus();
-    act(() => ReactTestUtils.Simulate.click(b!));
-    expect(root?.querySelector('button')).toBeFalsy();
+    it('mounts and unmounts without a dom', () => {
+      const component = renderer.create(<ContentWarningDynamic book={dummyBook} />);
+      expect(() => component.unmount()).not.toThrow();
+    });
   });
 });
diff --git a/src/app/content/components/ContentWarning.tsx b/src/app/content/components/ContentWarning.tsx
index 59491f713c..1cd6333e01 100644
--- a/src/app/content/components/ContentWarning.tsx
+++ b/src/app/content/components/ContentWarning.tsx
@@ -70,24 +70,26 @@ function WarningDivWithTrap({
 
 const useDismiss = (book: Book) => {
   const cookieKey = `content-warning-${book.id}`;
-  const [dismissed, setDismissed] = React.useState<string>(Cookies.get(cookieKey) || 'false');
+  const [isShown, setIsShown] = React.useState<boolean>(false);
 
   React.useEffect(() => {
-    setDismissed(Cookies.get(cookieKey) || 'false');
+    if (typeof window !== 'undefined') {
+      setIsShown(Cookies.get(cookieKey) !== 'true');
+    }
   }, [cookieKey]);
 
   const dismiss = React.useCallback(() => {
     Cookies.set(cookieKey, 'true', { expires: 28 });
-    setDismissed('true');
+    setIsShown(false);
   }, [cookieKey]);
 
-  return tuple(dismissed === 'true', dismiss);
+  return tuple(isShown, dismiss);
 };
 
 export default function ContentWarning({ book }: { book: Book }) {
-  const [dismissed, dismiss] = useDismiss(book);
+  const [isShown, dismiss] = useDismiss(book);
 
-  if (!hasOSWebData(book) || !book.content_warning_text || dismissed) {
+  if (!hasOSWebData(book) || !book.content_warning_text || !isShown) {
     return null;
   }
 
diff --git a/src/test/utils.ts b/src/test/utils.ts
index b6394113f3..45735a69c6 100644
--- a/src/test/utils.ts
+++ b/src/test/utils.ts
@@ -19,6 +19,7 @@ export const reactAndFriends = () => {
     Provider: require('react-redux').Provider,
     React: require('react'),
     ReactDOM: require('react-dom') as typeof import ('react-dom'),
+    ReactDOMTestUtils: require('react-dom/test-utils') as typeof import ('react-dom/test-utils'),
     Services: require('../app/context/Services'),
     TestContainer: require('./TestContainer').default,
     _jestStyledComponents: require('jest-styled-components'),