diff --git a/lib/index.js b/lib/index.js
index 1760b75ae..bfc1a637e 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -67,7 +67,8 @@ module.exports = function (source) {
   // module id for scoped CSS & hot-reload
   const shortFilePath = path
     .relative(context, resourcePath)
-    .replace(/^(\.\.[\\\/])+/, '') +
+    .replace(/\\/g, '/')
+    .replace(/^(\.\.\/)+/, '') +
     resourceQuery
 
   const id = hash(