diff --git a/src/findTestFiles.js b/src/findTestFiles.js
index c34be22..103a69f 100644
--- a/src/findTestFiles.js
+++ b/src/findTestFiles.js
@@ -4,5 +4,7 @@ export default async function findTestFiles(pattern) {
   const files = await glob(pattern, {
     ignore: ['**/node_modules/**', '**/dist/**', '**/build/**'],
   });
-  return files;
+
+  // Sort the files to make the output deterministic.
+  return files.sort((a, b) => a.localeCompare(b));
 }