diff --git a/lib/response.js b/lib/response.js
index <HASH>..<HASH> 100644
--- a/lib/response.js
+++ b/lib/response.js
@@ -70,7 +70,7 @@ res.send = function(body, status){
   }
 
   // populate Content-Length
-  if (!this.header('Content-Length')) {
+  if (undefined !== body && !this.header('Content-Length')) {
     this.header('Content-Length', Buffer.isBuffer(body)
       ? body.length
       : Buffer.byteLength(body));
Fixed [<I>]<I> support