In 2015, ‘marriage’ was redefined in the United States to include same-sex couples. In conceptual engineering, this is often assumed to be a paradigm case of Sally Haslanger’s (2020a, 2020b) semantic amelioration. Semantic amelioration changes a concept’s content to make it better. In the case of [MARRIAGE], [MARRIAGE]’s content was broadened to include same-sex couples – which, many contend, made it morally better. Semantic amelioration faces the following challenge, however: Doesn’t changing a concept’s content ‘change the subject?’ By broadening [MARRIAGE]’s (...) content to include same-sex couples in 2015, didn’t we replace [MARRIAGE] with a new concept that sounds and looks like [MARRIAGE] but nevertheless isn’t [MARRIAGE] – something like, [MARRIAGE*]? This is the topic continuity problem (TCP). Here, TCP assumes content essentialism about concepts, i.e., that a concept’s content is essential to it. Thus, since semantic amelioration changes concepts’ contents to make them better, semantic amelioration necessarily replaces concepts, according to this version of TCP. Haslanger recently resists this notion, however. Instead of embracing content essentialism about concepts, Haslanger embraces functional essentialism about concepts – that a concept’s function is essential to it. And since semantic amelioration leaves a concept’s function unchanged, Haslanger denies that semantic amelioration is conceptual replacement. In this paper, I argue that Haslanger’s functional essentialism integrally links concepts’ functions to their contents, such that changing a concept’s content requires changing its function, on Haslanger’s account. Therefore, semantic amelioration still replaces concepts even on Haslanger’s functional essentialism. I think this is avoided, however, if we incorporate Amie Thomasson’s (2020) recent work on concepts into Haslanger’s. Combining Thomasson’s work with Haslanger’s yields a new functional essentialism about concepts – called proper functional essentialism. Proper functional essentialism allows that some functional changes in concepts don't replace them, and hence, it perhaps reveals how to actually not change the subject in semantic amelioration. (shrink)