if it ain't broke, don't fix it

• if it ain't broken, don't fix it
• if it ain't busted, don't fix it

Attested at least since 1962,[1] originally Southern United States English; popularized by T. Bert Lance in May 1977.[2]

if it ain't broke, don't fix it

1. Leave something alone; avoid attempting to correct, fix, or improve what is already sufficient (often with an implication that the attempted improvement is risky and might backfire).

   I know it’s an ugly-looking antenna, but it gets the job done, and if it ain't broke, don't fix it.

• leave well enough alone

• don’t change a winning team
• don’t change horses in midstream
• don’t mess with success
• let sleeping dogs lie