补牢顾犬

Explanation: Lost sheep, the sheep pen before repair; met with the hare, only call the dog back to the hunt. Metaphor for the occurrence of mistakes, in time to remedy. 　　Source: Language of the "Warring States Chu policy four": "see rabbit and dog care, late than never; lost sheep and fill in prison, not to late too." 　　Examples: And to be open factory system to do, ~, has felt its late. ★ Qing Zuo, "Please expand by sparse ship gun manufacturers"