diff --git a/src/ifcconvert/XmlSerializer.cpp b/src/ifcconvert/XmlSerializer.cpp
index ba084f5a84..702e5431f1 100644
--- a/src/ifcconvert/XmlSerializer.cpp
+++ b/src/ifcconvert/XmlSerializer.cpp
@@ -119,7 +119,7 @@ typename V::list::ptr get_related(T* t, F f, G g) {
 	typename V::list::ptr acc(new typename V::list);
 	for (typename U::list::it it = li->begin(); it != li->end(); ++it) {
 		U* u = *it;
-		acc->push((*u.*g)());
+		acc->push((*u.*g)()->as<V>());
 	}
 	return acc;
 }
@@ -142,9 +142,15 @@ void descend(IfcProduct* product, ptree& tree) {
 		}
 	}
 
+#ifdef USE_IFC2x3
 	IfcObjectDefinition::list::ptr structures = get_related
 		<IfcProduct, IfcRelDecomposes, IfcObjectDefinition>
 		(product, &IfcProduct::IsDecomposedBy, &IfcRelDecomposes::RelatedObjects);
+#else
+	IfcObjectDefinition::list::ptr structures = get_related
+		<IfcProduct, IfcRelAggregates, IfcObjectDefinition>
+		(product, &IfcProduct::IsDecomposedBy, &IfcRelAggregates::RelatedObjects);
+#endif
 
 	for (IfcObjectDefinition::list::it it = structures->begin(); it != structures->end(); ++it) {
 		IfcObjectDefinition* ob = *it;
@@ -172,9 +178,15 @@ template <>
 void descend(IfcProject* project, ptree& tree) {
 	ptree& child = format_entity_instance(project, tree);
 	
+#ifdef USE_IFC2x3
 	IfcObjectDefinition::list::ptr structures = get_related
 		<IfcProject, IfcRelDecomposes, IfcObjectDefinition>
 		(project, &IfcProject::IsDecomposedBy, &IfcRelDecomposes::RelatedObjects);
+#else
+	IfcObjectDefinition::list::ptr structures = get_related
+		<IfcProject, IfcRelAggregates, IfcObjectDefinition>
+		(project, &IfcProduct::IsDecomposedBy, &IfcRelAggregates::RelatedObjects);
+#endif
 	
 	for (IfcObjectDefinition::list::it it = structures->begin(); it != structures->end(); ++it) {
 		IfcObjectDefinition* ob = *it;
diff --git a/src/ifcparse/IfcUtil.cpp b/src/ifcparse/IfcUtil.cpp
index ec87125610..c5fa4a0244 100644
--- a/src/ifcparse/IfcUtil.cpp
+++ b/src/ifcparse/IfcUtil.cpp
@@ -25,11 +25,15 @@
 #include "IfcUtil.h"
 
 void IfcEntityList::push(IfcUtil::IfcBaseClass* l) {
-	if ( l ) ls.push_back(l);
+	if (l) {
+		ls.push_back(l);
+	}
 }
 void IfcEntityList::push(const IfcEntityList::ptr& l) {
-	for( it i = l->begin(); i != l->end(); ++i  ) {
-		if ( *i ) ls.push_back(*i);
+	if (l) {
+		for( it i = l->begin(); i != l->end(); ++i  ) {
+			if ( *i ) ls.push_back(*i);
+		}
 	}
 }
 unsigned int IfcEntityList::size() const { return (unsigned int) ls.size(); }
diff --git a/src/ifcparse/IfcUtil.h b/src/ifcparse/IfcUtil.h
index b811a680a7..565f19f439 100644
--- a/src/ifcparse/IfcUtil.h
+++ b/src/ifcparse/IfcUtil.h
@@ -80,6 +80,13 @@ namespace IfcUtil {
 		virtual IfcSchema::Type::Enum getArgumentEntity(unsigned int i) const = 0;
 		virtual Argument* getArgument(unsigned int i) const = 0;
 		virtual const char* getArgumentName(unsigned int i) const = 0;
+
+		template <class T>
+		typename T* as() {
+			return is(T::Class()) 
+				? static_cast<T*>(this) 
+				: static_cast<T*>(0);
+		}
 	};
 
 	class IfcBaseEntity : public IfcBaseClass {
@@ -127,8 +134,8 @@ class IfcTemplatedEntityList {
 public:
 	typedef SHARED_PTR< IfcTemplatedEntityList<T> > ptr;
 	typedef typename std::vector<T*>::const_iterator it;
-	void push(T* t) {if (t) ls.push_back(t);}
-	void push(ptr t) { for ( typename T::list::it it = t->begin(); it != t->end(); ++it ) push(*it); }
+	void push(T* t) { if (t) { ls.push_back(t); } }
+	void push(ptr t) { if (t) { for ( typename T::list::it it = t->begin(); it != t->end(); ++it ) push(*it); } }
 	it begin() { return ls.begin(); }
 	it end() { return ls.end(); }
 	unsigned int size() const { return (unsigned int) ls.size(); }
@@ -162,15 +169,17 @@ public:
 	typedef SHARED_PTR< IfcEntityListList > ptr;
 	typedef std::vector< std::vector<IfcUtil::IfcBaseClass*> >::const_iterator outer_it;
 	typedef std::vector<IfcUtil::IfcBaseClass*>::const_iterator inner_it;
-	void push(const std::vector<IfcUtil::IfcBaseClass*>& l) { 
+	void push(const std::vector<IfcUtil::IfcBaseClass*>& l) {
 		ls.push_back(l); 
 	}
 	void push(const IfcEntityList::ptr& l) { 
-		std::vector<IfcUtil::IfcBaseClass*> li;
-		for (std::vector<IfcUtil::IfcBaseClass*>::const_iterator jt = l->begin(); jt != l->end(); ++jt) {
-			li.push_back(*jt); 
-		} 
-		push(li); 
+		if (l) {
+			std::vector<IfcUtil::IfcBaseClass*> li;
+			for (std::vector<IfcUtil::IfcBaseClass*>::const_iterator jt = l->begin(); jt != l->end(); ++jt) {
+				li.push_back(*jt); 
+			} 
+			push(li); 
+		}
 	}
 	outer_it begin() const { return ls.begin(); }
 	outer_it end() const { return ls.end(); }