diff --git a/src/ThreadRunner.cs b/src/ThreadRunner.cs
index 62048d4..19c9c65 100644
--- a/src/ThreadRunner.cs
+++ b/src/ThreadRunner.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Threading;
 
 namespace DCFApixels.DragonECS