zéi​qù​guān​mén

to lock the door after the thief has left

Senses

贼去关门/ 賊去關門 zéi​qù​guān​mén to lock the door after the thief has left

To take precautions only after a disaster or loss has already occurred; similar to the English idiom "to lock the stable door after the horse has bolted".

References

synonym 贼去关门/賊去關門 亡羊补牢/亡羊補牢
variant 贼去关门/賊去關門 贼出关门/賊出關門
variant 贼去关门/賊去關門 贼走关门/賊走關門