diff --git a/index.js b/index.js
index 2838c33..a83d8db 100644
--- a/index.js
+++ b/index.js
@@ -45,4 +45,5 @@ function generateWorld(shapes) {
   let runner = Runner.create();
   // run the engine
   Runner.run(runner, engine);
+  Composite.clear();
 }