diff --git a/lib/Lib/Core/Http.js b/lib/Lib/Core/Http.js
index 5ee489e9..afae2c01 100644
--- a/lib/Lib/Core/Http.js
+++ b/lib/Lib/Core/Http.js
@@ -135,7 +135,7 @@ var Http = module.exports = Class(function(){
       var filename = this.req.headers[C('post_ajax_filename_header')];
       var deferred = getDefer();
       var filepath = C('post_file_upload_path') || (os.tmpdir() + '/thinkjs_upload');
-      var name = crypto.randomBytes(20).toString('base64').replace(/\+/g, '_').replace(/\//g, '-');
+      var name = crypto.randomBytes(20).toString('base64').replace(/\+/g, '_').replace(/\//g, '_');
       mkdir(filepath);
       filepath += '/' + name + path.extname(filename);
       var stream = fs.createWriteStream(filepath);