diff --git a/MatterControlLib/SlicerConfiguration/EngineMappingsMatterSlice.cs b/MatterControlLib/SlicerConfiguration/EngineMappingsMatterSlice.cs
index 0e6c10543..599f5835a 100644
--- a/MatterControlLib/SlicerConfiguration/EngineMappingsMatterSlice.cs
+++ b/MatterControlLib/SlicerConfiguration/EngineMappingsMatterSlice.cs
@@ -324,7 +324,7 @@ namespace MatterHackers.MatterControl.SlicerConfiguration
 				if (supportObjects.Any())
 				{
 					// add a flag to the merge rules to let us know there was support
-					mergeRules += "S" + AddObjectsForExtruder(supportObjects, holes, outputOptions, ref savedStlCount);
+					mergeRules += "S" + AddObjectsForExtruder(supportObjects, null, outputOptions, ref savedStlCount);
 				}
 
 				var wipeTowerObjects = meshItemsOnBuildPlate.Where((item) => item.WorldOutputType() == PrintOutputTypes.WipeTower);
@@ -639,7 +639,7 @@ namespace MatterHackers.MatterControl.SlicerConfiguration
                     }
 				}
 
-				if (holes.Any())
+				if (holes?.Any() == true)
 				{
 					bool firstHole = true;