Corrective comments posted in response to misinformation shared on social media are not only effective in reducing belief in misinformation among those observing the interaction but also serve as a publicly observable social punishment against fake news sharing. We suggest that, by visibly displaying punishing behavior, corrective comments have the potential to function as a norm nudge, updating observers' perception of the norms regulating punishment, the socalled "meta-norms". We conducted a preregistered online experiment in which participants joined discussions resembling an online forum and could comment on posts shared by previous users. We manipulated participants' possibility to observe corrective comments replying to a post sharing fake news and measured the effect of this variation on their propensity to leave a corrective comment. We show that participants exposed to posts corrected by other users are significantly more likely to reply with a corrective comment, even after controlling for participants' perceived accuracy of the shared post. Participants exposed to the corrections provided by previous users perceive replying with corrections as more socially appropriate. Our results suggest that social corrections work as a (meta) norm nudge, increasing the probability of punishing norm violations by increasing the social appropriateness of correcting. Our findings suggest that interventions targeting "would-be"enforcers could complement existing policies specifically directed at norm violators.