On Wednesday at 23:00 UTC (19:00 EDT), flight controllers began to notice a tiny pressure leak in the ISS.
Although that sounds terrifying, the team made the call to not wake the crew up, as they weren't in any direct danger.
The next morning, the team probably woke up to some surprising (and slightly worrying) news, and all crew members went searching for the hole.
"An emergency situation occurred on the ISS at night and in the morning: a drop in pressure and an air leak aboard the station. Measures were taken to determine the origin of the leak," explained Dmitry Rogozin, Head of Russia's State Space Corporation Roscosmos, in a TASS report.
"The US crew gathered in the Russian segment and subsequently compartments were sealed off one by one to understand what happened and where. As a result, we localised the problem."
They eventually discovered that the leak was coming from a 2 millimeter hole in the Russian segment of the ISS, the upper section of the Soyuz MS-09 spacecraft – which is currently attached to the Rassvet module.
Although that was fine for the moment, it definitely wasn't a permanent fix.
"Soyuz commander Sergey Prokopyev of Roscosmos used epoxy on a gauze wipe to plug the hole identified as the leak source," says NASA on a blog post.
"As the teams were discussing options, flight controllers in Moscow performed a partial increase of the station's atmosphere using the ISS Progress 70 cargo ship's oxygen supply."
So for now it looks like the Expedition 56 crew are probably safe, although flight controllers are continuing to monitor the pressure, just in case something does go wrong.
They also need to determine what caused the leak, but at this stage, there's no information released about what might have happened.
But, according to NASA: "All station systems are stable and the crew is planning to return to its regular schedule of work on Friday."
Sounds like all in a day's work for the ISS crew.