@@ -30,6 +30,7 @@ function createThemeFile({
 	}
 
 	const CSSModulesData = themedWidgets.map(({ themeKey, fileName }) => {
+		themeKey = themeKey.split(/[\\]+/).join('/');
 		const CSSModulePath = `${themeKey}/${fileName}${CSSModuleExtension}`;
 		const themeKeyVariable = camelcase(fileName);
 
 
@@ -1,5 +1,6 @@
 import * as mockery from 'mockery';
 import * as sinon from 'sinon';
+import { join } from 'path';
 
 const { describe, it, beforeEach, afterEach } = intern.getInterface('bdd');
 const { assert } = intern.getPlugin('chai');
@@ -46,7 +47,10 @@ describe('The main runner', () => {
 			errorMessage = err;
 		}
 
-		assert.equal(errorMessage, 'Error: This package path does not exist: node_modules/some-package/theme');
+		assert.equal(
+			errorMessage,
+			'Error: This package path does not exist: ' + join('node_modules', 'some-package', 'theme')
+		);
 	});
 
 	it('errors if no widgets selections are made', async () => {
Original file line number	Diff line number	Diff line change
`@@ -30,6 +30,7 @@ function createThemeFile({`
`30`	`30`	`}`
`31`	`31`
`32`	`32`	`const CSSModulesData = themedWidgets.map(({ themeKey, fileName }) => {`
	`33`	`+ themeKey = themeKey.split(/[\\]+/).join('/');`
`33`	`34`	const CSSModulePath = `${themeKey}/${fileName}${CSSModuleExtension}`;
`34`	`35`	`const themeKeyVariable = camelcase(fileName);`
`35`	`36`