diff --git a/scripts/prepublish.mjs b/scripts/prepublish.mjs
index 292c0ebd3..a2afb4da1 100644
--- a/scripts/prepublish.mjs
+++ b/scripts/prepublish.mjs
@@ -93,13 +93,17 @@ const downloadMicrobitHex = async () => {
     const absoluteGeneratedDir = path.join(basePath, relativeGeneratedDir);
     fs.mkdirSync(absoluteGeneratedDir, {recursive: true});
     const absoluteGeneratedFile = path.join(basePath, relativeGeneratedFile);
+    const requirePath = `./${path
+        .relative(relativeGeneratedDir, relativeHexFile)
+        .split(path.win32.sep)
+        .join(path.posix.sep)}`;
     fs.writeFileSync(
         absoluteGeneratedFile,
         [
             '// This file is generated by scripts/prepublish.mjs',
             '// Do not edit this file directly',
             '// This file relies on a loader to turn this `require` into a URL',
-            `module.exports = require('./${path.relative(relativeGeneratedDir, relativeHexFile)}');`,
+            `module.exports = require('${requirePath}');`,
             '' // final newline
         ].join('\n')
     );