Changes have been passed to South Australia's electoral laws to stop minor party or independent candidates being elected to the state's upper house through dodgy preference deals.
The changes allow voters to continue to vote above or below the line as in past elections, by selecting one box above and at least 12 boxes below.
But after that, it will go no further.
"Once a vote is exhausted within that group or groups of candidates, it will not flow on to others through secret preferences," Attorney-General John Rau said on Wednesday.
"There will now be zero chance of candidates being accidentally elected using preference whispering."
The changes will be in force for next year's state election in March.