diff --git a/src/Builtin/Worlds.cs b/src/Builtin/Worlds.cs
index a817c39..157eb73 100644
--- a/src/Builtin/Worlds.cs
+++ b/src/Builtin/Worlds.cs
@@ -9,10 +9,10 @@
 
     public sealed class EcsDefaultWrold : EcsWorld<EcsDefaultWrold>
     {
-        public EcsDefaultWrold(EcsPipeline pipeline) : base(pipeline) { }
+        public EcsDefaultWrold(EcsPipeline pipeline = null) : base(pipeline) { }
     }
     public sealed class EcsEventWrold : EcsWorld<EcsDefaultWrold>
     {
-        public EcsEventWrold(EcsPipeline pipeline) : base(pipeline) { }
+        public EcsEventWrold(EcsPipeline pipeline = null) : base(pipeline) { }
     }
 }