OpenSprinkler › Forums › OpenSprinkler Unified Firmware › OSPi 2.1.9 build errors › Reply To: OSPi 2.1.9 build errors April 9, 2020 at 1:03 pm #65060 Dutchie30Participant A very late reply from me: Adding #include <stdlib.h> (Thx @Marc!) fixed the issue for me too. I’m all for including this in the next release.