diff --git a/lib/ejs.js b/lib/ejs.js
index b011424d..c9b104c5 100755
--- a/lib/ejs.js
+++ b/lib/ejs.js
@@ -611,6 +611,10 @@ Template.prototype = {
     if (opts.debug) {
       console.log(src);
     }
+    if (opts.compileDebug && opts.filename) {
+      src = src + '\n'
+        + '//# sourceURL=' + opts.filename + '\n';
+    }
 
     try {
       if (opts.async) {