diff --git a/src/ifcparse/IfcEntityList.h b/src/ifcparse/IfcEntityList.h
index 72ecac8d0c..3953a29715 100644
--- a/src/ifcparse/IfcEntityList.h
+++ b/src/ifcparse/IfcEntityList.h
@@ -50,6 +50,7 @@ public:
 	}
 	void remove(IfcUtil::IfcBaseClass*);
 	IfcEntityList::ptr filtered(const std::set<IfcSchema::Type::Enum>& entities);
+	IfcEntityList::ptr unique();
 };
 
 template <class T>
diff --git a/src/ifcparse/IfcUtil.cpp b/src/ifcparse/IfcUtil.cpp
index c07fff5379..abda4e25cd 100644
--- a/src/ifcparse/IfcUtil.cpp
+++ b/src/ifcparse/IfcUtil.cpp
@@ -62,6 +62,7 @@ void IfcEntityList::remove(IfcUtil::IfcBaseClass* instance) {
 		ls.erase(it);
 	}
 }
+
 IfcEntityList::ptr IfcEntityList::filtered(const std::set<IfcSchema::Type::Enum>& entities) {
 	IfcEntityList::ptr return_value(new IfcEntityList);
 	for (it it = begin(); it != end(); ++it) {
@@ -79,6 +80,18 @@ IfcEntityList::ptr IfcEntityList::filtered(const std::set<IfcSchema::Type::Enum>
 	return return_value;
 }
 
+IfcEntityList::ptr IfcEntityList::unique() {
+	std::set<IfcUtil::IfcBaseClass*> encountered;
+	IfcEntityList::ptr return_value(new IfcEntityList);
+	for (it it = begin(); it != end(); ++it) {
+		if (encountered.find(*it) == encountered.end()) {
+			return_value->push(*it);
+			encountered.insert(*it);
+		}
+	}
+	return return_value;
+}
+
 
 unsigned int IfcUtil::IfcBaseType::getArgumentCount() const { return 1; }
 Argument* IfcUtil::IfcBaseType::getArgument(unsigned int i) const { return entity->getArgument(i); }