diff --git a/fetch.js b/fetch.js
index e4dbf1b246c61ff4947fbafa5c9e19e9aed639f2..2abd34715174ea7fe40df009d7c556ad81646082 100644
--- a/fetch.js
+++ b/fetch.js
@@ -267,7 +267,7 @@
 
   function headers(xhr) {
     var head = new Headers()
-    var pairs = xhr.getAllResponseHeaders().trim().split('\n')
+    var pairs = (xhr.getAllResponseHeaders() || '').trim().split('\n')
     pairs.forEach(function(header) {
       var split = header.trim().split(':')
       var key = split.shift().trim()