diff --git includes/ajax.inc includes/ajax.inc
index a119e17..f270a0e 100644
--- includes/ajax.inc
+++ includes/ajax.inc
@@ -602,12 +602,18 @@ function ajax_pre_render_element($element) {
         $element['#ajax']['event'] = 'blur';
         break;
 
-      case 'radio':
-      case 'checkbox':
       case 'select':
         $element['#ajax']['event'] = 'change';
         break;
 
+      // Ideally we would fire an AJAX request for radios and checkboxes when
+      // they change, instead of every time they're clicked. However, IE doesn't
+      // fire change events the same as other browsers. For radio and checkbox
+      // elements, the change event fires only on blur. The workaround is to
+      // react on the click event instead of the change event.
+      // @see http://www.quirksmode.org/dom/events/change.html#t04
+      case 'radio':
+      case 'checkbox':
       case 'link':
         $element['#ajax']['event'] = 'click';
         break;