Firefox was originally released for Mac OS X 10.0 and higher.[163] The minimum OS then increased to Mac OS X 10.2 in Firefox 1.5 and 10.4 in Firefox 3.[164][165] Firefox 4 dropped support for Mac OS X 10.4 and PowerPC Macs, and Firefox 17 dropped support for Mac OS X 10.5 entirely.[166][167] The system requirements were left unchanged until 2016, when Firefox 49 dropped support for Mac OS X 10.6–10.8.[168][169] Most recently, Mozilla ended support for OS X 10.9–10.11 in Firefox 79, with those users being supported on the Firefox 78 ESR branch until July 2021.[170][171][172]