diff --git a/src/ecs/ecs.hpp b/src/ecs/ecs.hpp
index d448479..5f5c313 100644
--- a/src/ecs/ecs.hpp
+++ b/src/ecs/ecs.hpp
@@ -119,7 +119,6 @@ class ECS
 	void updateSystems(ECSSystemList& systems, float delta);
 	
 private:
-	Array<BaseECSSystem*> systems;
 	Map<uint32, Array<uint8>> components;
 	Array<std::pair<uint32, Array<std::pair<uint32, uint32> > >* > entities;
 
diff --git a/src/ecs/ecsSystem.cpp b/src/ecs/ecsSystem.cpp
index 98738ba..79267d0 100644
--- a/src/ecs/ecsSystem.cpp
+++ b/src/ecs/ecsSystem.cpp
@@ -1,6 +1,6 @@
 #include "ecsSystem.hpp"
 
-bool BaseECSSystem::isValid()
+bool BaseECSSystem::isValid() const
 {
 	for(uint32 i = 0;  i < componentFlags.size(); i++) {
 		if((componentFlags[i] & BaseECSSystem::FLAG_OPTIONAL) == 0) {
diff --git a/src/ecs/ecsSystem.hpp b/src/ecs/ecsSystem.hpp
index 15b29bd..c8d90d9 100644
--- a/src/ecs/ecsSystem.hpp
+++ b/src/ecs/ecsSystem.hpp
@@ -11,15 +11,15 @@ class BaseECSSystem
 	};
 	BaseECSSystem() {}
 	virtual void updateComponents(float delta, BaseECSComponent** components) {}
-	const Array<uint32>& getComponentTypes()
+	const Array<uint32>& getComponentTypes() const
 	{
 		return componentTypes;
 	}
-	const Array<uint32>& getComponentFlags()
+	const Array<uint32>& getComponentFlags() const
 	{
 		return componentFlags;
 	}
-	bool isValid();
+	bool isValid() const;
 protected:
 	void addComponentType(uint32 componentType, uint32 componentFlag = 0)
 	{
@@ -42,7 +42,7 @@ class ECSSystemList
 		systems.push_back(&system);
 		return true;
 	}
-	inline size_t size() {
+	inline size_t size() const {
 		return systems.size();
 	}
 	inline BaseECSSystem* operator[](uint32 index) {