diff --git a/lib/OpenLayers/Request.js b/lib/OpenLayers/Request.js
index 227af6d82f..3a5865bc0a 100644
--- a/lib/OpenLayers/Request.js
+++ b/lib/OpenLayers/Request.js
@@ -129,7 +129,8 @@ OpenLayers.Request = {
         // header through the user we cannot use applyDefaults, but have to 
         // check manually whether we were called with a "X-Requested-With"
         // header.
-        var customRequestedWithHeader = false;
+        var customRequestedWithHeader = false,
+            headerKey;
         for(headerKey in config.headers) {
             if (config.headers.hasOwnProperty( headerKey )) {
                 if (headerKey.toLowerCase() === 'x-requested-with') {