Lena Dunham doesn't want to get married until same-sex marriage is legalised in every state in America.

The 'Girls' creator and star has been in a relationship with Fun.'s Jack Antonoff for two years but, although she'd like to get hitched at some point, she refuses to tie the knot until her sister Grace, who is a lesbian, is able to exchange vows with her girlfriend.

Speaking on SiriusXM radio show, she said: ''We're not against marriage, but I wanna wait until it's something... my sister's gay and it just doesn't feel good to me to do something she can't do. She can do it in some places but not all places.''

Brad Pitt and Angelina Jolie and Kristen Bell and Dax Shepard also made the same promise in the past but both couples have since got married after 19 states - including California - legalised gay marriage last year.

Brad and Angelina - who have six children together, three biological and three adopted - got married in France in August following 10 years of dating.

Dax and Kristen, who have 18-month-old daughter Lincoln and one on the way, have been dating since 2007 and got engaged in 2010, but held off tying the knot until last year as they wanted to wait until same-sex marriage was legalised in California.