diff --git a/js/ui/screenShield.js b/js/ui/screenShield.js
index 07e450f8f..e10ef346b 100644
--- a/js/ui/screenShield.js
+++ b/js/ui/screenShield.js
@@ -579,13 +579,14 @@ const ScreenShield = new Lang.Class({
     showDialog: function() {
         // Ensure that the stage window is mapped, before taking a grab
         // otherwise X errors out
-        Meta.later_add(Meta.LaterType.BEFORE_REDRAW, Lang.bind(this, function() {
+        let actorShownId = 0;
+        actorShownId = this.actor.connect('show', Lang.bind(this, function() {
             if (!this._isModal) {
                 Main.pushModal(this.actor);
                 this._isModal = true;
             }
 
-            return false;
+            this.actor.disconnect(actorShownId);
         }));
 
         this.actor.show();