Voice shopping with Walmart and Google is officially here.

The world’s largest retailer in August said it would start offering a chunk of its inventories for sale on the Google Express shopping site and app, as well as on the Google Home smart speaker through voice shopping. Timed to Google’s hardware launch event Wednesday, Walmart said customers can now start shopping  for more than 2 million Walmart items via those channels.

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As an added incentive to test out voice shopping, Walmart said it will give customers a $25 coupon off a future Walmart order if they buy a Google Home or new Google Home Mini from Walmart when they link their accounts to Google Express.

Voice shopping is still a new arena in commerce, with few customers testing it out. But, Walmart and Google are hopefully they can team up to build a base in the area before Amazon takes over. Amazon essentially invented the voice shopping market and has a dominant position in the smart speaker market with its Echo family of devices.

The $25 coupon deal is available only in the contiguous US and can only be used for Walmart orders through Google Express. Devices must be activated no later than Jan. 15, 2018.

The announcement comes just a day after Walmart accidentally offered an early peek at its preorder page for the Google Home Mini, just before the new device was unveiled Wednesday.