Qld voting change 'not so clever': Green

The Queensland government's sudden tactical move to reintroduce compulsory preferential voting may backfire given the re-emergence of One Nation, respected election analyst Antony Green says.

In April, Labor amended an opposition bill to increase the number of seats in parliament by scrapping optional preferential voting.

While it fuelled accusations the party had broken an election promise to be a consultative government, the move was hailed by commentators as a masterstroke that would help it retain power at the next state poll, due by early 2018.

But Mr Green said the minority government made that change assuming the Greens would be the most significant minor party at the next election.

"I think what looked like a very clever move ... for the Labor party back in the middle of the year, I don't think looks quite as clever now," he told ABC radio on Monday.

Mr Green said the change was driven by concern that Green preferences had "a habit of exhausting rather than flowing through to the Labor party".

But the 2015 election was an exception, he added.

"One Nation's preferences under full preferential voting may be even more important than they were back in 1998," he said.

In that election, Pauline Hanson's party won 11 seats.

"What I'm saying is that the assumption that full preferential voting would help Labor is not necessarily something you can be certain of," Mr Green said.

The opposition bill that was amended by Labor would increase the number of seats from 89 to 93 and the boundaries would be finalised 90 days after their release in early 2017.

Mr Green said that could influence the timing of the next state poll because if the government wanted an election on the current boundaries - which would favour sitting members - it would need to call the election in the first three months of next year.

"I suspect it will be in 2017," he said.

"I think it's highly unlikely they'll hang around till 2018."