diff --git a/lib/plugins/tag/include_code.js b/lib/plugins/tag/include_code.js
index 7e06c44e10..bee71acd26 100644
--- a/lib/plugins/tag/include_code.js
+++ b/lib/plugins/tag/include_code.js
@@ -10,7 +10,8 @@ var extend = hexo.extend,
   hexofs = hexo.util.file,
   path = require("path");
 
-var code_prefix = '/downloads/code';
+var code_prefix = '/downloads/code',
+    code_path = path.join(hexo.source_dir, config.code_dir);
 
 var regex = {
   captionTitleFile:/(.*)?(\s+|^)(\/*\S+)/i,
@@ -33,36 +34,37 @@ extend.tag.register('include_code', function(args, content) {
     title = match[1];
     file = match[3];
   } else {
-    throw "File could not be found";
+    throw new Error("File could not be found");
   }
 
-  var local = path.join(config.code_dir, file);
+  var local = path.join(code_path, file);
   var url = path.join(code_prefix, file);
 
-  if (!fs.existsSync(config.code_dir) || !fs.existsSync(local)) {
-    throw "File '" + local + "'could not be found";
+  if (!fs.existsSync(code_path) || !fs.existsSync(local)) {
+    throw new Error("File '" + local + "' could not be found");
   }
 
-  if (fs.lstatSync(config.code_dir).isSymbolicLink()) {
-    throw "Code directory '" + config.code_dir + "' cannot be a symlink";
+  if (fs.lstatSync(code_path).isSymbolicLink()) {
+    throw new Error("Code directory '" + config.code_dir + "' cannot be a symlink");
   }
 
   var code = fs.readFileSync(local).toString();
 
+  title = title || path.basename(file);
+  lang = lang || path.extname(file).replace('.', '');
   caption = '<span>' + title + '</span> <a href="' + url + '">download</a>';
   return highlight(code, {lang: lang, caption:caption, gutter: lineNumConfig, tab: tabConfig});
 });
 
 extend.generator.register(function(locals, render, callback) {
-  hexofs.dir(config.code_dir, function(files) {
+  hexofs.dir(code_path, function(files) {
     for (var i in files) {
       var file = files[i];
       var url = path.join(code_prefix, file);
-      var local = path.join(config.code_dir, file);
+      var local = path.join(code_path, file);
       var code = fs.readFileSync(local).toString();
       hexo.route.set(url, code);
     }
     callback();
   });
 });
-