diff --git a/include/Screeps/Room.hpp b/include/Screeps/Room.hpp
index 4360990..cbf7c5f 100644
--- a/include/Screeps/Room.hpp
+++ b/include/Screeps/Room.hpp
@@ -61,19 +61,16 @@ public:
 	template <class T>
 	std::vector<std::unique_ptr<RoomObject>> find(std::function<bool(const T&)> predicate = {}) const
 	{
-		std::vector<std::unique_ptr<RoomObject>> objects = find(T::findConstant);
 		if (predicate)
-			objects.erase(std::remove_if(objects.begin(), objects.end(),
-			                             [predicate](const std::unique_ptr<RoomObject>& object)
-			                             {
-				                             if (auto* ptr = dynamic_cast<T*>(object.get()))
-					                             return !predicate(*ptr);
-				                             else
-					                             return true;
-			                             }),
-			              objects.end());
-
-		return objects;
+		{
+			auto p = [&](const JS::Value& value)
+			{
+				return predicate(T(value));
+			};
+			return find(T::findConstant, p);
+		}
+		else
+			return find(T::findConstant);
 	}
 
 	int findExitTo(const std::string& room);
diff --git a/src/RoomObject.cpp b/src/RoomObject.cpp
index d58d64a..31dfcd3 100644
--- a/src/RoomObject.cpp
+++ b/src/RoomObject.cpp
@@ -63,36 +63,42 @@ std::unique_ptr<RoomObject> createRoomObject(JS::Value object)
 	};
 
 	// FIXME: sort by rarity
-	if (is("StructureRoad"))
-		return std::make_unique<StructureRoad>(std::move(object));
-	else if (is("StructureWall"))
-		return std::make_unique<StructureWall>(std::move(object));
-	else if (is("StructureRampart"))
-		return std::make_unique<StructureRampart>(std::move(object));
-	else if (is("StructureExtension"))
-		return std::make_unique<StructureExtension>(std::move(object));
+	if (is("Structure"))
+	{
+		std::string type = object["structureType"].as<std::string>();
+		if (type == Screeps::STRUCTURE_ROAD)
+			return std::make_unique<StructureRoad>(std::move(object));
+		else if (type == Screeps::STRUCTURE_WALL)
+			return std::make_unique<StructureWall>(std::move(object));
+		else if (type == Screeps::STRUCTURE_RAMPART)
+			return std::make_unique<StructureRampart>(std::move(object));
+		else if (type == Screeps::STRUCTURE_EXTENSION)
+			return std::make_unique<StructureExtension>(std::move(object));
+		else if (type == Screeps::STRUCTURE_CONTAINER)
+			return std::make_unique<StructureContainer>(std::move(object));
+		else if (type == Screeps::STRUCTURE_TOWER)
+			return std::make_unique<StructureTower>(std::move(object));
+		else if (type == Screeps::STRUCTURE_LINK)
+			return std::make_unique<StructureLink>(std::move(object));
+		else if (type == Screeps::STRUCTURE_SPAWN)
+			return std::make_unique<StructureSpawn>(std::move(object));
+		else if (type == Screeps::STRUCTURE_CONTROLLER)
+			return std::make_unique<StructureController>(std::move(object));
+		else if (type == Screeps::STRUCTURE_STORAGE)
+			return std::make_unique<StructureStorage>(std::move(object));
+		else if (type == Screeps::STRUCTURE_EXTRACTOR)
+			return std::make_unique<StructureExtractor>(std::move(object));
+		else
+			return nullptr;
+	}
 	else if (is("Creep"))
 		return std::make_unique<Creep>(std::move(object));
-	else if (is("StructureContainer"))
-		return std::make_unique<StructureContainer>(std::move(object));
 	else if (is("Source"))
 		return std::make_unique<Source>(std::move(object));
 	else if (is("ConstructionSite"))
 		return std::make_unique<ConstructionSite>(std::move(object));
-	else if (is("StructureTower"))
-		return std::make_unique<StructureTower>(std::move(object));
-	else if (is("StructureLink"))
-		return std::make_unique<StructureLink>(std::move(object));
-	else if (is("StructureSpawn"))
-		return std::make_unique<StructureSpawn>(std::move(object));
 	else if (is("Ruin"))
 		return std::make_unique<Ruin>(std::move(object));
-	else if (is("StructureController"))
-		return std::make_unique<StructureController>(std::move(object));
-	else if (is("StructureStorage"))
-		return std::make_unique<StructureStorage>(std::move(object));
-	else if (is("StructureExtractor"))
-		return std::make_unique<StructureExtractor>(std::move(object));
 	else if (is("Deposit"))
 		return std::make_unique<Deposit>(std::move(object));
 	else if (is("Flag"))