diff --git a/intellihide.js b/intellihide.js
index 8fb1e97..30f0a0d 100644
--- a/intellihide.js
+++ b/intellihide.js
@@ -335,7 +335,7 @@ var Intellihide = Utils.defineClass({
     },
 
     _checkIfGrab: function() {
-        if (GrabHelper._grabHelperStack.some(gh => gh._owner == this._dtpPanel.panel.actor)) {
+        if (GrabHelper._grabHelperStack && GrabHelper._grabHelperStack.some(gh => gh._owner == this._dtpPanel.panel.actor)) {
             //there currently is a grab on a child of the panel, check again soon to catch its release
             this._timeoutsHandler.add([T1, CHECK_GRAB_MS, () => this._queueUpdatePanelPosition()]);