A Wairarapa couple who joked on the night about winning a $12.5 million Lotto prize waited a week to check their ticket - and now they're laughing all the way to the bank.

The prize had Masterton abuzz for over a week after the winning numbers were drawn on March 17. The couple bought the ticket at Kuripuni Lotto and Post Shop.

The lucky couple, who wished to remain anonymous, had purchased the ticket when they were in Masterton earlier this month.

"I spotted Kuripuni Lotto and Post Shop while we were in town and just knew I had to get a ticket – they're such a lucky store," they said

It took the winners several days to check their ticket - despite knowing they had picked it up from the winning store.

"I finally had a bit of time, so grabbed my phone and scanned the ticket using the Lotto NZ App. It whirled for a second, then 'Major Prize' popped up on my screen – I couldn't believe it," they said.

The couple decided to sit on their good news for several days, to let it sink in before they claimed the prize.

"When we found the store had sold the big one, my husband turned to me and said 'Did you get a ticket there?'," the winner said.

The couple did not yet have plans as to how they would spend the money, but called it a "blessing" for themselves and their family.

"She turned to me and said, 'Of course – and it's the winning one'. We both cracked up, not realising how right she was," her husband said.