diff --git a/lib/incoming_form.js b/lib/incoming_form.js
index 9fffa48f..8eed298c 100644
--- a/lib/incoming_form.js
+++ b/lib/incoming_form.js
@@ -182,7 +182,7 @@ IncomingForm.prototype.onPart = function(part) {
 IncomingForm.prototype.handlePart = function(part) {
   var self = this;
 
-  if (part.filename === undefined) {
+  if (!part.filename) {
     var value = ''
       , decoder = new StringDecoder(this.encoding);