diff --git a/content/treestyletab/res/fullScreenCanvas.xul b/content/treestyletab/res/fullScreenCanvas.xul
index f6021212..59c46fd4 100644
--- a/content/treestyletab/res/fullScreenCanvas.xul
+++ b/content/treestyletab/res/fullScreenCanvas.xul
@@ -130,6 +130,8 @@ window.addEventListener('DOMContentLoaded', function() {
 		init : function() {
 			var canvas = document.createElementNS('http://www.w3.org/1999/xhtml', 'canvas');
 			canvas.setAttribute('id', 'fullScreenCanvas-canvas');
+			canvas.setAttribute('width', '0');
+			canvas.setAttribute('height', '0');
 			canvas.setAttribute('style', 'width:0;height:0;');
 			if (!this.isGecko19) {
 				this.container.appendChild(canvas);