I have two classes, both of which need to be able to call the same instance of entitymanager class Engine { EntityManager::Entitymanager EManager; } And I need to add an object to a vector contained by this particular instance of Engine. What I want to do is be able to add a bullet spawned by the player to the vector that contains all my entities. class Player : Entity { void SpawnBullet() {Engine::EManager.Add(BULLET);} } The above returns this error: error: object missing in reference to ‘Engine::EManager’ How do I resolve this? Any help or pointers in the right direction would be much appreciated!