Astronauts used tape to temporarily patch up an air leak discovered on the Russian side of the International Space Station.
Officials said the gap had caused a small loss in cabin pressure and was "isolated to a hole about two millimetres in diameter".
It was temporarily plugged with heat resistant tape but astronauts were later able to do a more permanent fix.
NASA and Russian officials stressed the six astronauts were not in any danger.
"The rate of the leak was slowed… through the temporary application of Kapton tape at the leak site," said NASA as the initial repairs were done.
"Flight controllers are working with the crew to develop a more comprehensive long-term repair.
"Once the patching is complete, additional leak checks will be performed. All station systems are stable, and the crew is in no danger…"
The leak, detected on Wednesday night, could be the result of a micrometeorite strike, according to Russian officials.
"Overnight and in the morning there was an abnormal situation – a pressure drop, an oxygen leak at the station," said Roscosmos chief Dmitry Rogozin.
"A micro fracture was found, most likely it is damage from the outside. The design engineers believe it is the result of a micrometeorite."
It was found in the most recent Soyuz capsule, which is one of two docked at the space station and is home to three Americans, two Russians and a German.
Mr Rogozin said the leak would be patched up from the inside.
NASA said the problem had caused a "minute pressure leak".
It later added: "Flight controllers at their respective Mission Control centres in Houston and Moscow worked together with the crew to effect a repair option in which Soyuz commander Sergey Prokopyev of Roscosmos used epoxy on a gauze wipe to plug the hole identified as the leak source.
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"Flight controllers in Houston are continuing to monitor the station's cabin pressure in the wake of the repair.
"All station systems are stable and the crew is planning to return to its regular schedule of work on Friday."