Dustin Lance Black takes the wind out of Sam Smith's Oscar sails and tells him to stop texting his fiancé Tom Daley

British singer-songwriter Sam Smith, winner for Best Original Song for "Writing's on the Wall" from the movie "Spectre", gestures at the Governors Ball following the 88th Academy Awards in Hollywood, California February 28, 2016. REUTERS/Lucy Nicholson

Aoife Kelly

Sam Smith has been receiving a lot of flack over his Best Original Song win at the Oscars, not least from Dustin Lance Black.

Smith won the Oscar for 'Writing's on the Wall' which he penned as Bond film Spectre's theme tune, beating Lady Gaga's Till It Happens to You from The Hunting Ground and Earned it from 50 Shades of Grey.

During his acceptance speech he said, “I read an article a few months ago by Sir Ian McKellen, and he said that no openly gay man had ever won an Oscar, and if this is the case, even if it isn’t the case, I want to dedicate this to the LGBT community all around the world.”

McKellan, however, had been specifically referring to the Best Actor Oscar.

Previous winners in the Best Original Song category alone include gay men Elton John and Stpehen Sondheim.  Howard Ashman also won two Oscars for best Original Song and Melisas Etheridge won in 2006.

Dustin Lance Black also won for screenwriting in 2009 for Milk and he wasn't going to let this one go...

Tom Daley and Dustin Lance Black . (Photo by Gareth Cattermole/Getty Images)

"Hey @SamSmithWorld, if you have no idea who I am, it may be time to stop texting my fiancé," he wrote on Twitter, attaching a link to his own Oscars acceptance speech.

By his fiance he is referring to British Olympic diver Tom Daley.

Awkward.

According to Entertainment Weekly, when he was told of his mistake backstage, Smith said, "S**t! F*** that!  Two's my lucky number, so it's all good.  Who was the other person?"

Reaction on Twitter has been unsurprisingly hilarious.