Contemporary evidence suggests that masculinity is changing, adopting perceived feminine traits in the process. Implications of this new masculine norm on gender relations remain unclear. Our research aims to better understand the influence of changing masculine norms on men’s endorsement of gender-hierarchy-legitimizing ideologies. Based on Precarious Manhood Theory and Social Role Theory, we conducted two quasi-experimental studies ( N = 412) in which we first assessed heterosexual men's motivation to protect traditional masculinity. Then, we informed them that men’s gender norms are becoming more feminine (feminization norm condition) or are remaining masculine in a traditional sense (traditional norm condition). In the third (baseline-control) condition, participants received no information about men’s gender norms. Finally, we assessed the extent to which participants endorsed gender-hierarchy-legitimizing ideologies, namely sexism (Study 1) and masculinist beliefs (Study 2). Results showed that men who were less motivated to protect traditional masculinity were less likely to endorse gender-hierarchy-legitimizing ideologies when exposed to the feminization and control conditions compared to the traditional norm condition. The implications of these findings for gender equality and gender relations are discussed.