diff --git a/src/utils/gl.ts b/src/utils/gl.ts
index 0831628..fbd451e 100644
--- a/src/utils/gl.ts
+++ b/src/utils/gl.ts
@@ -20,7 +20,7 @@ interface GlOption {
 
 export default class GL {
   ctx!: WebGLRenderingContext
-  private el!: HTMLCanvasElement
+  protected el!: HTMLCanvasElement
   program!: WebGLProgram | null
 
   private vertexShader!: WebGLShader