diff --git a/lib/form/yui/dateselector/dateselector.js b/lib/form/yui/dateselector/dateselector.js
index db1445a27d0..bb04e7466e7 100644
--- a/lib/form/yui/dateselector/dateselector.js
+++ b/lib/form/yui/dateselector/dateselector.js
@@ -204,8 +204,11 @@ YUI.add('moodle-form-dateselector', function(Y) {
                 bodyContent : Y.Node.create('<div id="dateselector-calendar-content"></div>'),
                 id : 'dateselector-calendar-panel'
             });
-            this.panel.removeAttr('zIndex'); // z-index is set by the theme.
             this.panel.render(document.body);
+            // zIndex is added by panel.render() and is set to 0.
+            // Remove zIndex from panel, as this should be set by CSS. This can be done by removeAttr but
+            // ie8 fails and there is know issue for it.
+            Y.one('#dateselector-calendar-panel').setStyle('zIndex', null);
             this.panel.on('heightChange', this.fix_position, this);
 
             Y.one('#dateselector-calendar-panel').on('click', function(e){e.halt();});