dbo.Users and dbo.aspnet_users

i have a mvc4 vs 11 beta project using an old windows authentication database, when i try to login i get the {"Invalid object name 'dbo.Users'."} errro because the tables are named with the aspnet_ prefix.
I cant really rename the tables, is there a workaround for this. can i tell forms authentication to use prefix? maybe in the connection sting?

Thanks