diff --git a/lib/gen-id.js b/lib/gen-id.js
index 25281ae..8c9621d 100644
--- a/lib/gen-id.js
+++ b/lib/gen-id.js
@@ -1,8 +1,8 @@
 // utility for generating a uid for each component file
 // used in scoped CSS rewriting
-var fileUid = 1
-var fileRegistry = Object.create(null)
+var hash = require('hash-sum')
+var cache = Object.create(null)
 
 module.exports = function genId (file) {
-  return fileRegistry[file] || (fileRegistry[file] = fileUid++)
+  return cache[file] || (cache[file] = hash(file))
 }