diff --git a/FilterExtension/ConfigNodes/customCategory.cs b/FilterExtension/ConfigNodes/customCategory.cs
index 051f6c2b..51d206d3 100644
--- a/FilterExtension/ConfigNodes/customCategory.cs
+++ b/FilterExtension/ConfigNodes/customCategory.cs
@@ -196,7 +196,10 @@ private void generateEngineTypes()
                 }
                 engines.Add(name);
             }
-            subCategories.AddUniqueRange(engines);
+            if (subCategories != null)
+                subCategories.AddUniqueRange(engines);
+            else
+                subCategories = engines;
         }
 
         private void makeTemplate(ConfigNode node)
diff --git a/GameData/000_FilterExtensions/FilterExtensions.dll b/GameData/000_FilterExtensions/FilterExtensions.dll
index 99f0eba3..0e07d4f7 100644
Binary files a/GameData/000_FilterExtensions/FilterExtensions.dll and b/GameData/000_FilterExtensions/FilterExtensions.dll differ