What do you do when you run into your friend on their birthday? You wish them a happy birthday, of course!

Or wait—you wish … him or her a happy birthday? When you run into your friend on … his or her birthday? That's how you’re supposed to say it if you want to avoid using they to refer to one person, but it’s a bit wordy and awkward. You could use just him or her alone, but what if you don’t want to be specific about the sex of the referent? You could make it plural—“what do you do when you run into friends on their birthdays”—but that sounds a bit strange, like there’s a whole group of friends having their birthdays at once. Anyone who writes for a living runs into this situation all the time, and must go through all kinds of contortions to avoid the easiest solution: singular they.

In everyday speech, singular they, the use of they/them to refer to one person, feels completely natural. But in more formal contexts, and in writing, that usage has long been frowned upon. And not just frowned upon, but banned as ungrammatical. However, it is not ungrammatical in the same way as “I didn’t knowed that” or “what are you cook for dinner tonight?” Those sentences don’t sound natural in any context.

Proponents of singular they have long argued that the prohibition makes no sense. Not only is it natural, it has been used in English for centuries. It’s in the King James Bible. Authors like Chaucer, Shakespeare, Swift, Austen, Thackeray, and Shaw used it. Before the production of school textbooks for grammar in the 19th century, no one complained about it or even noticed it. Avoiding it is awkward or necessitates sexist language.

Now, in the most recent update to The Washington Post style guide, singular they has been given official approval. Post copy editor Bill Walsh explains that he personally accepted singular they many years ago, but had stopped short of allowing it in the paper. He finally decided to endorse it in house style after coming to the conclusion that it is “the only sensible solution to English’s lack of a gender-neutral third-person singular personal pronoun.”

Other institutions are sure to follow suit. Professional associations of copy editors have been chafing at the restriction against it for years, and now that a major publication has approved it, it won’t be long before more do the same. The news of the acceptance of singular they may cause a little stir, but nobody will notice the change in action, as Walsh says, “I suspect that the singular they will go largely unnoticed even by those who oppose it on principle. We’ve used it before, if inadvertently, and I’ve never heard a complaint.”

A grammar “mistake”? In a newspaper? That no one complained about? Unthinkable! That’s the final and perhaps most convincing sign that singular they really isn’t a mistake at all.