In this article, we analyze how a music genre is reciprocally defined online, through the crowdsourced ‘facts’ of Wikipedia. What are the traditional implicit and explicit exclusionary practices in this sort of genre formation? And how can internet-specific sociabilities create new exclusionary practices in the process of defining music? By analyzing the edit history of Wikipedia’s ‘hyperpop’ page, we locate ongoing debates, controversies, and contestations that point to shaping forces around online genre formation. These potentially have a huge impact on how hyperpop is understood both inside and outside of the music community. In locating the most active editors of the hyperpop Wikipedia page and scrutinizing their edit histories as well as the discussions on the hyperpop page itself, we uncovered debates about artistic notability, biases toward specific sources, and attempts at associating or dissociating musical genre from non-musical identities (such as race, gender, and nationality). In sum, we aimed to investigate the main controversies involved in the Wikipedia definition of hyperpop for what they can tell us about both the process of online genre formation and the very nature of collective knowledge-making spaces.