Communications Minister Malcolm Turnbull is sure Treasurer Joe Hockey followed the rules when he made 13 taxpayer-funded trips to Cairns while in opposition.

According to News Corp reports, Mr Hockey's trips to Cairns, where he owns a farm, cost more than $20,000.

"Joe Hockey like all MPs and Senators has to acquit their expenses [and] use their travel entitlements they've got in a manner consistent with the rules, and I'm sure he has," Mr Turnbull told reporters.

Speaker Bronwyn Bishop's controversial luxury helicopter ride to a Liberal Party fundraiser has prompted calls for changes to rules around parliamentarians' expenses.

Mr Turnbull said while some areas of the rules were "ambiguous", he didn't see a need for major changes.

"I think the issue is one of compliance and commonsense rather than having to make a big change to the rules per se," he said.

"We've got to make sure that what we're doing is strictly in our parliamentary business."