diff --git a/src/ifcgeom/kernels/cgal/CgalKernel.h b/src/ifcgeom/kernels/cgal/CgalKernel.h
index 1ac193a673..d3b2703606 100644
--- a/src/ifcgeom/kernels/cgal/CgalKernel.h
+++ b/src/ifcgeom/kernels/cgal/CgalKernel.h
@@ -112,7 +112,7 @@ namespace kernels {
 		bool convert(const taxonomy::shell* l, cgal_shape_t& shape);
 
 		virtual bool convert_impl(const taxonomy::shell*, ifcopenshell::geometry::ConversionResults&);
-		virtual bool convert_impl(const taxonomy::extrusion*, ifcopenshell::geometry::ConversionResults&);
+		// virtual bool convert_impl(const taxonomy::extrusion*, ifcopenshell::geometry::ConversionResults&);
 	};
 
 }
diff --git a/src/ifcgeom/schema/mapping.cpp b/src/ifcgeom/schema/mapping.cpp
index dd7a605dae..2ce140442f 100644
--- a/src/ifcgeom/schema/mapping.cpp
+++ b/src/ifcgeom/schema/mapping.cpp
@@ -176,6 +176,13 @@ taxonomy::item* mapping::map_impl(const IfcSchema::IfcFace* inst) {
 			if (!bound->Orientation()) {
 				r->reverse();
 			}
+			if (bound->declaration().is(IfcSchema::IfcFaceOuterBound::Class())) {
+				// Make a copy in case we need immutability later for e.g. caching
+				auto s = r->clone();
+				((taxonomy::loop*)s)->external = true;
+				delete r;
+				r = s;
+			}
 			face->children.push_back(r);
 		}		
 	}
diff --git a/src/ifcgeom/schema_agnostic/IfcGeomIterator.h b/src/ifcgeom/schema_agnostic/IfcGeomIterator.h
index cc6bc32823..feb28af639 100644
--- a/src/ifcgeom/schema_agnostic/IfcGeomIterator.h
+++ b/src/ifcgeom/schema_agnostic/IfcGeomIterator.h
@@ -219,6 +219,7 @@ namespace ifcopenshell { namespace geometry {
 
 			task_iterator_ = tasks_.begin();
 
+			task_result_index_ = 0;
 			done = 0;
 			total = tasks_.size();