I argue that the growing-block theory of time and truthmaker maximalism jointly entail that some truthmakers undergo mereological change as time passes. Central to my argument is a grounding-based account of what I call the “purely incremental” nature of the growing-block theory of time. As I will show, the argument presented in this paper suggests that growing-block theorists endorsing truthmaker maximalism have reasons to take composition to be restricted and the “block” of reality to literally grow as time goes by.