diff --git a/lib/ejs.js b/lib/ejs.js
index f746d915..f89c3605 100644
--- a/lib/ejs.js
+++ b/lib/ejs.js
@@ -106,7 +106,7 @@ includeSource = function (path, options) {
   return templ.source;
 };
 
-function rethrow(err, str, filename, lineno){
+rethrow = function (err, str, filename, lineno){
   var lines = str.split('\n')
     , start = Math.max(lineno - 3, 0)
     , end = Math.min(lines.length, lineno + 3);