diff --git a/ObservatoryExplorer/CustomCriteriaManager.cs b/ObservatoryExplorer/CustomCriteriaManager.cs
index cfa9d2e..df52544 100644
--- a/ObservatoryExplorer/CustomCriteriaManager.cs
+++ b/ObservatoryExplorer/CustomCriteriaManager.cs
@@ -271,7 +271,7 @@ namespace Observatory.Explorer
 
         private void LuaGC()
         {
-            LuaState.DoString("collectgarbage()");
+            LuaState?.DoString("collectgarbage()");
         }
 
         internal class Parent