A system and method for last known good (LKG) for patches. A file cache is created to store binaries which have shipped as part of a previous wide public release—security fixes (GDRs) and service packs. There are two levels of cache, including an SP cache which keeps all of the files which were shipped as part of the service pack, and a GDR cache which keeps all of the files shipped in the GDRs. Customers do not need to download all of the binaries contained in a package when they already have the version of the dependent binaries on their system when they get the new patch. Customers only need to test the binaries which have changed, rather than everything in the new package, which speeds up the deployment of critical patches.