2014-10-29 OS X
Caffeine is an awesome application that in case of any need will prevent your Mac from going to sleep mode.
Unfortunately Caffeine’s icons have not been designed for Retina displays and on Macs with Retina all you will see will be pixelated cup (of coffee obviously).
Once your icons are downloaded, extract them to be able to copy png files.
When done, proceed to you Applications directory and look for Caffeine.app. Right click and select Show Package Contents.
Now follow to Contents/Resources and copy all png icons into that directory. When a prompt window will appear, click Replace to overwrite existing icons.
Below is the final content of Resources after you copied required icons.
To allow changes take effect. Quit Caffeine and reopen it again. See the difference?
You have done well! Go get some coffee. ;) Jimmy, thank you!