diff --git a/misc/ajax.js b/misc/ajax.js
index 339d167ebe56044b7bb474c60bd0cb3d60196640..a9588261bb543ece85787d5a7d8307fea3639b7d 100644
--- a/misc/ajax.js
+++ b/misc/ajax.js
@@ -132,7 +132,7 @@ Drupal.ajax = function (base, element, element_settings) {
       // Sanity check for browser support (object expected).
       // When using iFrame uploads, responses must be returned as a string.
       if (typeof response == 'string') {
-        response = $.parseJson(response);
+        response = $.parseJSON(response);
       }
       return ajax.success(response, status);
     },