diff --git a/lib/OpenLayers/Layer/Grid.js b/lib/OpenLayers/Layer/Grid.js
index 70986215f4..36cf1023ed 100644
--- a/lib/OpenLayers/Layer/Grid.js
+++ b/lib/OpenLayers/Layer/Grid.js
@@ -42,7 +42,6 @@ OpenLayers.Layer.Grid.prototype =
     destroy: function() {
         this.clearGrid();
         this.grid = null;
-        this.alpha = null;
         this.tileSize = null;
         OpenLayers.Layer.HTTPRequest.prototype.destroy.apply(this, arguments); 
     },