if it ain't broke don't fix it
Don't meddle with something that's functioning adequately. For example, So long as they like our proposal let's not change it; if it ain't broke don't fix it. This folksy and deliberately ungrammatical expression dates from the mid-1900s. For a synonym, see leave well enough alone.
Words nearby if it ain't broke don't fix it
ieper,
ieyasu,
if,
if anything,
if at first you don't succeed, try, try again,
if it ain't broke don't fix it,
if music be the food of love, play on,
if only,
if the mountain will not come to muhammad, then muhammad will go to the mountain,
if the mountain won't come to muhammad, muhammad must go to the mountain,
if the shoe fits, wear it