No matter what E.L. James tells you, the professional world still values the ability to write well–and that invaluable skill includes the nearly forgotten art of copy editing. We mention this fact because sometimes tiny little errors can be both costly and embarrassing.

In case you don’t live in New York City (congratulations), the Metropolitan Transportation Authority just earned the ill will of all eight million of us city folk by raising the price of a single subway fare from $2.25 to $2.50. The MTA’s communications team, however, does not appear to have received the message: the organization printed out thousands of updated maps that still listed the minimum price of a pay-per-ride subway card at $4.50 (it’s now $5).

Of course, all those thousands of maps are now useless. The price to correct this incredibly simple mistake? A quarter of a million dollars. That may not be a lot for an organization that serves so many people every day, but it does give us a great opportunity to make a point: your voice matters. Whether writing materials for yourself, your firm or your client, make sure you edit everything twice. Misspellings on your own Facebook page are fine–but awful as grammar and punctuation on the social network may be, those errors never cost anybody so much for so little.