Don’t fix bugs later; fix them now.
- Steve Maguire, Writing Solid Code: Microsoft's Techniques for Developing Bug-Free C Programs by Steve Maguire , ISBN: 1556155514
 
Normal people believe that if it ain't broke, don't fix it. Engineers believe that if it ain't broke, it doesn't have enough features yet.
- Scott Adams
 
If the code doesn't bother you, don't bother it.
- Anonymous
 
Don't fix it if it ain't broke.
- Anonymous - Proverbial. This one has often been applied to maintenance programming.