Legislation to clamp down on legal highs is being amended so that animal testing can only be used as a last resort.
Parliament's health select committee on Friday reported back on the Psychoactive Substances Bill, which requires legal high manufacturers to prove that their products are safe before they can be sold.
The Minister responsible for the bill, Todd McClay, has inserted a clause saying any psychoactive product test mustn't rely on research, testing or teaching involving an animal if a suitable alternative exists.
The select committee had previously said such a clause was outside the scope of the bill.
The Green Party says it's delighted by the change but will continue to push for a further amendment, to stop any data from animal testing being used.
The Government is fast-tracking the bill so it can be passed next month.