diff --git a/qi81k80v08.js b/qi81k80v08.js
index d9c3594..2fa77d7 100644
--- a/qi81k80v08.js
+++ b/qi81k80v08.js
@@ -158,7 +158,7 @@ this.enemies = this.enemies.reduce(
         enemy.mesh.position.add(enemy.velocity);
         enemy.mesh.updateInstancePosition();
 
-        enemy.mesh.quaterion.angle.add(enemy.rotation.angle);
+        enemy.mesh.quaterion.angle += enemy.rotation.angle;
 		enemy.mesh.updateInstanceRotation();
 		
         enemy.lifeTime += data.delta;