diff --git a/ChangeLog b/ChangeLog
index 5eec27b2f4..514cfc0676 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -4,6 +4,7 @@ phpMyAdmin - ChangeLog
 4.2.8.0 (not yet released)
 - bug #4516 Odd export behavior
 - bug #4519 Uncaught TypeError: Cannot read property 'success' of null
+- bug #4520 sql.js: cannot read property
 
 4.2.7.1 (2014-08-17)
 - bug #4501 [security] XSS in table browse page
diff --git a/js/sql.js b/js/sql.js
index aad4a454e8..aa4ca3b346 100644
--- a/js/sql.js
+++ b/js/sql.js
@@ -284,7 +284,7 @@ AJAX.registerOnload('sql.js', function () {
         PMA_prepareForAjaxRequest($form);
 
         $.post($form.attr('action'), $form.serialize(), function (data) {
-            if (data.success === true) {
+            if (typeof data !== 'undefined' && data.success === true) {
                 // success happens if the query returns rows or not
                 //
                 // fade out previous messages, if any
@@ -373,7 +373,7 @@ AJAX.registerOnload('sql.js', function () {
                         }
                     }
                 }
-            } else if (data.success === false) {
+            } else if (typeof data !== 'undefined' && data.success === false) {
                 // show an error message that stays on screen
                 $('#sqlqueryform').before(data.error);
                 $sqlqueryresults.hide();