diff --git a/simulation.lisp b/simulation.lisp
index ce2c793..3065ceb 100644
--- a/simulation.lisp
+++ b/simulation.lisp
@@ -14,6 +14,9 @@
 (defgeneric update (simulation dt))
 (defgeneric render (simulation))
 
+(defmethod initialize-instance :after ((sim simulation) &key)
+  (start sim))
+
 (defmethod run ((sim simulation))
   (sdl2:make-this-thread-main
    (lambda ()