diff --git a/handlers/html.go b/handlers/html.go
index 6b1554f..ad38f00 100644
--- a/handlers/html.go
+++ b/handlers/html.go
@@ -82,7 +82,7 @@ var htmlWebGL = `
var image = new Image();
ws.onopen = function() {
- var gl = canvas.getContext("webgl",{antialias:false}) || canvas.getContext("experimental-webgl");
+ var gl = document.getElementById('canvas').getContext('webgl',{antialias:false}) || canvas.getContext('experimental-webgl');
var vertexShaderSrc =
"attribute vec2 aVertex;" +