diff --git a/packages/react-scripts/scripts/utils/createJestConfig.js b/packages/react-scripts/scripts/utils/createJestConfig.js
index abfd92c8d3c..786f4d0bf31 100644
--- a/packages/react-scripts/scripts/utils/createJestConfig.js
+++ b/packages/react-scripts/scripts/utils/createJestConfig.js
@@ -14,7 +14,7 @@ const paths = require('../../config/paths');
 module.exports = (resolve, rootDir, isEjecting) => {
   // Use this instead of `paths.testsSetup` to avoid putting
   // an absolute filename into configuration after ejecting.
-  const setupTestsMatches = paths.testsSetup.match(/src\/setupTests\.(.+)/);
+  const setupTestsMatches = paths.testsSetup.match(/src[/\\]setupTests\.(.+)/);
   const setupTestsFileExtension =
     (setupTestsMatches && setupTestsMatches[1]) || 'js';
   const setupTestsFile = fs.existsSync(paths.testsSetup)