A Melbourne cafe went viral on social media this week after introducing an 18 percent ¡°man tax¡± to raise awareness of Australia¡¯s gender pay gap.

The gender surcharge at the Handsome Her cafe is optional and the proceeds are donated to a women¡¯s charity, cafe owner Alexandra O¡¯Brien told the Seven Network.

¡°One week out of every month we have an 18 percent premium for men, which is the same amount as the gender pay gap,¡± O¡¯Brien said.

The pay gap has ranged between 15 percent and 19 percent for the last two decades, the Australian Government Workplace Gender Equality Agency says on its website.

O¡¯Brien said the response from male customers had been positive.

¡°If people aren¡¯t comfortable with paying it, or men don¡¯t want to pay it, we¡¯re not going to kick them out the door,¡± she said. ¡°It¡¯s just a good opportunity to do some good.¡±