diff --git a/www/js/draw-scene.js b/www/js/draw-scene.js
index 6405916..0df76cc 100644
--- a/www/js/draw-scene.js
+++ b/www/js/draw-scene.js
@@ -1,4 +1,7 @@
 function drawScene(gl, programInfo, buffers, time) {
+  // Tell WebGL how to convert from clip space to pixels
+  gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);
+
   gl.clearColor(0.0, 0.0, 0.0, 1.0); // Clear to black, fully opaque
   gl.clearDepth(1.0);                // Clear everything
   gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
@@ -21,8 +24,8 @@ function drawScene(gl, programInfo, buffers, time) {
   // Viewport resolution in pixels
   gl.uniform2f(
     programInfo.uniformLocations.resolution,
-    gl.drawingBufferWidth,
-    gl.drawingBufferHeight,
+    gl.canvas.width,
+    gl.canvas.height,
   );
 
   {