diff --git a/lib/plugins/processor/asset.js b/lib/plugins/processor/asset.js
index 29b3259204..ee39ade154 100644
--- a/lib/plugins/processor/asset.js
+++ b/lib/plugins/processor/asset.js
@@ -3,7 +3,7 @@
 const common = require('./common');
 const Promise = require('bluebird');
 const yfm = require('hexo-front-matter');
-const { extname } = require('path');
+const { extname, relative } = require('path');
 const { Pattern } = require('hexo-util');
 
 module.exports = ctx => {
@@ -84,7 +84,7 @@ module.exports = ctx => {
   }
 
   function processAsset(file) {
-    const id = file.source.substring(ctx.base_dir.length).replace(/\\/g, '/');
+    const id = relative(ctx.base_dir, file.source).replace(/\\/g, '/');
     const Asset = ctx.model('Asset');
     const doc = Asset.findById(id);