Hailey and Justin Bieber. (Source: Bang Showbiz)

Hailey Bieber is not having twins.

The 27-year-old model announced this week that she and her husband are expecting their first baby together but an unfortunate typo from her mother-in-law Pattie Mallette led fans to believe that two babies are on the way.

In her congratulatory post, Pattie wrote: “Congratulations Grandpa! WE ARE GONNA HAVE THE CUTEST GRAND-BABIES EVER!”

One fan speculated that her wording meant that “more than one” baby is on the way, and another asked “wait, babies????”

But Pattie replied: “No not twins lol I wish. I just mean in general. Hopefully they will have more than one eventually. They will make beautiful babies whenever they have them. One is enough for now.”

The Ontario native said she had been “waiting for the day” they announced it and admitted she is “so excited” that she will soon be a grandmother. She said: “So I have been waiting for this day and now that they have shared it I can finally celebrate with ya’ll.

“Oh my gosh, I’m going to be a grandma. Oh my goodness!

“Justin and Hailey you are going to be the best parents ever and I am so excited. Oh my goodness. Praise God.”

The Peaches hitmaker and wife Hailey – who tied the knot in 2018 – announced their baby news with a montage on Instagram, which featured the pair renewing their wedding vows in Hawaii.

Among a series of behind-the-scenes snaps, Hailey is seen wearing a white lace dress that highlights her baby bump while Justin claimed that the pair are “thrilled” by the news.

The insider told Entertainment Tonight: “Hailey and Justin are thrilled to be expecting a baby together.

“They have wanted this for a long time and can’t wait to expand their family and bring a child into the world.”