SAG-AFTRA has warned its members that Hollywood studios may be short-changing actors on the travel provisions of its master contracts.

In a message to members Wednesday, the union said that the travel provisions of the contracts did not change during this year’s negotiations with the Alliance of Motion Picture and Television Producers and with TV networks.

SAG-AFTRA did not name a specific production. The AMPTP was not immediately available for comment.

“It’s important that you know that producers may not unilaterally rewrite these rules,” the alert said. “SAG-AFTRA intends to vigorously defend this contract provision using all means available. We are addressing this matter directly with the studios to ensure the proper administration of this provision in our agreement.”

SAG-AFTRA also said performers working on location should review carefully their time sheets and call sheets, and immediately advise the union of any discrepancies they find.

“We appreciate member inquiries about this issue and will keep you apprised as the situation unfolds,” the missive concluded.

During negotiations in 2010, SAG and AFTRA — which had not yet merged — agreed to eliminate the long-standing requirement that air transportation must be first class for sets less than 1,000 miles away. In exchange, SAG and AFTRA achieved 2% annual increases to minimum-wage rates and a hike in the health and pension contributions from 15% to 16.5%.