The worst kind of disappointment is being told that the ice cream machine is broken when you’re craving a McFlurry.

Most people know not to get their hopes up if they head to a McDonald’s for a McFlurry—it’s a running joke that the McDonald’s ice cream machine always seems to be broken when you swing by the drive-through. But why can’t McDonald’s get it together and give its customers what they want?

The main reason is that the McDonald’s ice cream machines take forever to clean, taking up to four hours to sanitize—and it has to be done every single day. When the machines are in the process of being cleaned, they can’t serve ice cream. And, when the staff is handing out Big Macs left and right, no one has the time to tend to the laborious machine. Telling you that the ice cream machine is broken instead of admitting that they are too lazy to clean it is just one of the secrets that fast-food workers won’t tell you.

In early 2017, McDonald’s announced that they were going to be replacing their soft serve machines with ones that are easier to maintain and wouldn’t take as long to clean. However, actually installing the new equipment in every restaurant is taking a very long time and customers are still complaining.

McDonald’s employees stand by the fact that cleaning the machines take forever and they often have to reject customer’s ice cream orders. One employee shared on Reddit that in her year and a half working at the chain, the ice cream machine has only legitimately been down one time, but they can’t sell ice cream because they’re always cleaning it.

So for now, you may have to keep your McFlurry cravings to a minimum until all of the new McDonald’s ice cream machines are in place. If you really can’t control yourself, an extremely fed up customer kindly created an app that lets you check if the ice cream machine is working at the McDonald’s closest to you. To satisfy your cravings, try something salty instead. This is the secret ingredient that makes their fries so delicious.