Nineteen Macau casino junket operators risk losing their ability to operate in the world’s largest gambling hub if they can’t step up their compliance game.

Speaking on the sidelines of this week’s Macau Gaming Show 2016, Gaming Inspection and Coordination Bureau (DICJ) chief Paulo Martins Chan said a review of Macau’s 145 approved junkets’ accounting systems had concluded that 19 operators’ practices were “unsatisfactory.”

Macau Business Daily quoted Chan saying the DICJ’s goal was to achieve “more regulated junket activity” and thus it was giving these 19 operators a window in which to improve their accounting practices. However, Chan warned that this window would close by “the end of the year.” This isn’t an empty threat, as the DICJ purged 35 junket operators in January for similar accounting shortcomings.

Speaking Tuesday at an MGS panel on junkets, Macao Polytechnic University associate professor Changbin Wang said the DICJ was “not aggressive enough” in soliciting information on the backgrounds of junket employees. Junket directors and shareholders with a stake above 5% stake must submit detailed paperwork to garner DICJ approval, but player reps and sub-agents must submit only their names and criminal records.