diff --git a/src/ifcgeom/IfcGeom.cpp b/src/ifcgeom/IfcGeom.cpp
index f235d9b07a..d0f17a46c8 100644
--- a/src/ifcgeom/IfcGeom.cpp
+++ b/src/ifcgeom/IfcGeom.cpp
@@ -991,7 +991,7 @@ std::pair<std::string, double> IfcGeom::Kernel::initializeUnits(IfcSchema::IfcUn
 		} else {
 			for (auto it = units->begin(); it != units->end(); ++it) {
 				IfcSchema::IfcUnit* base = *it;
-				if (base->declaration().is(IfcSchema::IfcNamedUnit::Class())) {
+				if (base->as<IfcSchema::IfcNamedUnit>()) {
 					IfcSchema::IfcNamedUnit* named_unit = base->as<IfcSchema::IfcNamedUnit>();
 					if (named_unit->UnitType() == IfcSchema::IfcUnitEnum::IfcUnit_LENGTHUNIT ||
 						named_unit->UnitType() == IfcSchema::IfcUnitEnum::IfcUnit_PLANEANGLEUNIT)
@@ -999,10 +999,10 @@ std::pair<std::string, double> IfcGeom::Kernel::initializeUnits(IfcSchema::IfcUn
 						std::string current_unit_name;
 						const double current_unit_magnitude = IfcParse::get_SI_equivalent<IfcSchema>(named_unit);
 						if (current_unit_magnitude != 0.) {
-							if (named_unit->declaration().is(IfcSchema::IfcConversionBasedUnit::Class())) {
-								IfcSchema::IfcConversionBasedUnit* u = (IfcSchema::IfcConversionBasedUnit*)base;
+							if (named_unit->as<IfcSchema::IfcConversionBasedUnit>()) {
+								IfcSchema::IfcConversionBasedUnit* u = named_unit->as<IfcSchema::IfcConversionBasedUnit>();
 								current_unit_name = u->Name();
-							} else if (named_unit->declaration().is(IfcSchema::IfcSIUnit::Class())) {
+							} else if (named_unit->as<IfcSchema::IfcSIUnit>()) {
 								IfcSchema::IfcSIUnit* si_unit = named_unit->as<IfcSchema::IfcSIUnit>();
 								if (si_unit->Prefix()) {
 									current_unit_name = IfcSchema::IfcSIPrefix::ToString(*si_unit->Prefix()) + unit_name;
diff --git a/src/ifcgeom/IfcGeom.h b/src/ifcgeom/IfcGeom.h
index 41cbce4802..42575acb3e 100644
--- a/src/ifcgeom/IfcGeom.h
+++ b/src/ifcgeom/IfcGeom.h
@@ -347,8 +347,8 @@ public:
 				if (surface_style->Side() != IfcSchema::IfcSurfaceSide::IfcSurfaceSide_NEGATIVE) {
 					auto styles_elements = surface_style->Styles();
 					for (auto mt = styles_elements->begin(); mt != styles_elements->end(); ++mt) {
-						if ((*mt)->declaration().is(T::Class())) {
-							return std::make_pair(surface_style, (T*) *mt);
+						if ((*mt)->as<T>())) {
+							return std::make_pair(surface_style, (*mt)->as<T>());
 						}
 					}
 				}
diff --git a/src/ifcgeom/IfcGeometricSet.cpp b/src/ifcgeom/IfcGeometricSet.cpp
index 7b4556d439..ce74dbe3dc 100644
--- a/src/ifcgeom/IfcGeometricSet.cpp
+++ b/src/ifcgeom/IfcGeometricSet.cpp
@@ -58,14 +58,14 @@ bool IfcGeom::Kernel::convert(const IfcSchema::IfcGeometricSet* l, IfcRepresenta
 
 		part_succes = true;
 		decltype(parent_style) style = 0;
-		if (element->declaration().is(IfcSchema::IfcPoint::Class())) {
-			style = get_style((IfcSchema::IfcPoint*) element);
+		if (element->as<IfcSchema::IfcPoint>()) {
+			style = get_style(element->as<IfcSchema::IfcPoint>());
 		}
-		else if (element->declaration().is(IfcSchema::IfcCurve::Class())) {
-			style = get_style((IfcSchema::IfcCurve*) element);
+		else if (element->as<IfcSchema::IfcPoint>()) {
+			style = get_style(element->as<IfcSchema::IfcPoint>());
 		}
-		else if (element->declaration().is(IfcSchema::IfcSurface::Class())) {
-			style = get_style((IfcSchema::IfcSurface*) element);
+		else if (element->as<IfcSchema::IfcPoint>()) {
+			style = get_style(element->as<IfcSchema::IfcPoint>());
 		}
 		shapes.push_back(IfcRepresentationShapeItem(l->data().id(), s, style ? style : parent_style));
 	}
diff --git a/src/ifcgeom/IfcIndexedPolyCurve.cpp b/src/ifcgeom/IfcIndexedPolyCurve.cpp
index 29ac4372ad..81ae655b2f 100644
--- a/src/ifcgeom/IfcIndexedPolyCurve.cpp
+++ b/src/ifcgeom/IfcIndexedPolyCurve.cpp
@@ -61,8 +61,8 @@ bool IfcGeom::Kernel::convert(const IfcSchema::IfcIndexedPolyCurve* l, TopoDS_Wi
 		auto segments = *l->Segments();
 		for (auto it = segments->begin(); it != segments->end(); ++it) {
 			auto segment = *it;
-			if (segment->declaration().is(IfcSchema::IfcLineIndex::Class())) {
-				IfcSchema::IfcLineIndex* line = (IfcSchema::IfcLineIndex*) segment;
+			if (segment->as<IfcSchema::IfcLineIndex>()) {
+				IfcSchema::IfcLineIndex* line = segment->as<IfcSchema::IfcLineIndex>();
 				std::vector<int> indices = *line;
 				gp_Pnt previous;
 				for (std::vector<int>::const_iterator jt = indices.begin(); jt != indices.end(); ++jt) {
@@ -80,8 +80,8 @@ bool IfcGeom::Kernel::convert(const IfcSchema::IfcIndexedPolyCurve* l, TopoDS_Wi
 					}
 					previous = current;
 				}
-			} else if (segment->declaration().is(IfcSchema::IfcArcIndex::Class())) {
-				IfcSchema::IfcArcIndex* arc = (IfcSchema::IfcArcIndex*) segment;
+			} else if (segment->as<IfcSchema::IfcArcIndex>()) {
+				IfcSchema::IfcArcIndex* arc = segment->as<IfcSchema::IfcArcIndex>();
 				std::vector<int> indices = *arc;
 				if (indices.size() != 3) {
 					throw IfcParse::IfcException("Invalid IfcArcIndex encountered");
@@ -103,7 +103,7 @@ bool IfcGeom::Kernel::convert(const IfcSchema::IfcIndexedPolyCurve* l, TopoDS_Wi
 					Logger::Warning("Ignoring segment on", l);
 				}
 			} else {
-				throw IfcParse::IfcException("Unexpected IfcIndexedPolyCurve segment of type " + segment->declaration().name());
+				throw IfcParse::IfcException("Unexpected IfcIndexedPolyCurve segment of type " + segment->as<IfcUtil::IfcBaseClass>()->declaration().name());
 			}
 		}
 	} else if (points.begin() < points.end()) {
diff --git a/src/ifcgeom/IfcShellBasedSurfaceModel.cpp b/src/ifcgeom/IfcShellBasedSurfaceModel.cpp
index ed2bb79007..0d78ceec64 100644
--- a/src/ifcgeom/IfcShellBasedSurfaceModel.cpp
+++ b/src/ifcgeom/IfcShellBasedSurfaceModel.cpp
@@ -28,8 +28,8 @@ bool IfcGeom::Kernel::convert(const IfcSchema::IfcShellBasedSurfaceModel* l, Ifc
 	for(auto it = shells->begin(); it != shells->end(); ++ it) {
 		TopoDS_Shape s;
 		decltype(collective_style) shell_style;
-		if ((*it)->declaration().is(IfcSchema::IfcRepresentationItem::Class())) {
-			shell_style = get_style((IfcSchema::IfcRepresentationItem*)*it);
+		if ((*it)->as<IfcSchema::IfcRepresentationItem>()) {
+			shell_style = get_style((*it)->as<IfcSchema::IfcRepresentationItem>());
 		}
 		if (convert_shape(*it,s)) {
 			shapes.push_back(IfcRepresentationShapeItem(l->data().id(), s, shell_style ? shell_style : collective_style));
diff --git a/src/ifcgeom/IfcTrimmedCurve.cpp b/src/ifcgeom/IfcTrimmedCurve.cpp
index 5b2081ad3c..77140a1e2a 100644
--- a/src/ifcgeom/IfcTrimmedCurve.cpp
+++ b/src/ifcgeom/IfcTrimmedCurve.cpp
@@ -85,11 +85,11 @@ bool IfcGeom::Kernel::convert(const IfcSchema::IfcTrimmedCurve* l, TopoDS_Wire&
 
 	for (auto it = trims1->begin(); it != trims1->end(); it ++ ) {
 		auto i = *it;
-		if ( i->declaration().is(IfcSchema::IfcCartesianPoint::Class()) ) {
-			IfcGeom::Kernel::convert((IfcSchema::IfcCartesianPoint*)i, pnts[sense_agreement] );
+		if (i->as<IfcSchema::IfcCartesianPoint>()) {
+			IfcGeom::Kernel::convert(i->as<IfcSchema::IfcCartesianPoint>(), pnts[sense_agreement] );
 			has_pnts[sense_agreement] = true;
-		} else if ( i->declaration().is(IfcSchema::IfcParameterValue::Class()) ) {
-			const double value = *((IfcSchema::IfcParameterValue*)i);
+		} else if (i->as<IfcSchema::IfcParameterValue>()) {
+			const double value = *i->as<IfcSchema::IfcParameterValue>();
 			flts[sense_agreement] = value * parameterFactor;
 			has_flts[sense_agreement] = true;
 		}
@@ -97,11 +97,11 @@ bool IfcGeom::Kernel::convert(const IfcSchema::IfcTrimmedCurve* l, TopoDS_Wire&
 
 	for (auto it = trims2->begin(); it != trims2->end(); it ++ ) {
 		auto i = *it;
-		if ( i->declaration().is(IfcSchema::IfcCartesianPoint::Class()) ) {
-			IfcGeom::Kernel::convert((IfcSchema::IfcCartesianPoint*)i, pnts[1-sense_agreement] );
+		if (i->as<IfcSchema::IfcCartesianPoint>()) {
+			IfcGeom::Kernel::convert(i->as<IfcSchema::IfcCartesianPoint>(), pnts[1-sense_agreement] );
 			has_pnts[1-sense_agreement] = true;
-		} else if ( i->declaration().is(IfcSchema::IfcParameterValue::Class()) ) {
-			const double value = *((IfcSchema::IfcParameterValue*)i);
+		} else if (i->as<IfcSchema::IfcParameterValue>()) {
+			const double value = *i->as<IfcSchema::IfcParameterValue>();
 			flts[1-sense_agreement] = value * parameterFactor;
 			has_flts[1-sense_agreement] = true;
 		}
diff --git a/src/ifcparse/aggregate_of_instance.h b/src/ifcparse/aggregate_of_instance.h
index 59f335f79d..c6bf8f5921 100644
--- a/src/ifcparse/aggregate_of_instance.h
+++ b/src/ifcparse/aggregate_of_instance.h
@@ -45,8 +45,11 @@ public:
 	template <class U>
 	typename U::list::ptr as() {
 		typename U::list::ptr r(new typename U::list);
-		const bool all = !U::Class().as_entity();
-		for (it i = begin(); i != end(); ++i) if (all || (*i)->declaration().is(U::Class())) r->push((U*)*i);
+		for (it i = begin(); i != end(); ++i) {
+			if ((*i)->as<U>()) {
+				r->push((*i)->as<U>());
+			}
+		}
 		return r;
 	}
 	void remove(IfcUtil::IfcBaseClass*);