diff --git a/src/SparkRenderer.ts b/src/SparkRenderer.ts
index 6d35c53..3596df3 100644
--- a/src/SparkRenderer.ts
+++ b/src/SparkRenderer.ts
@@ -418,7 +418,9 @@ export class SparkRenderer extends THREE.Mesh {
       );
     } else {
       // Rendering to the canvas or WebXR
-      const renderSize = renderer.getSize(this.uniforms.renderSize.value);
+      const renderSize = renderer.getDrawingBufferSize(
+        this.uniforms.renderSize.value,
+      );
       if (renderSize.x === 1 && renderSize.y === 1) {
         // WebXR mode on Apple Vision Pro returns 1x1 when presenting.
         // Use a different means to figure out the render size.