Hi @ellert, please rebase rather than merge. That way only your commits will show up. However, I think the current way you are handling the definitions is not optimal. We need to modernize the CMake to be target-based, and get the required flags via the INTERFACE_COMPILE_OPTIONS property from the targets, by using target_compile_options(...) then installing the targets. This needs a major refactoring of parts of the build system, so I my plan is to work on it for v6.0 next year. We can have a stopgap solution in between, but we need to ensure that the build system and XRootDConfig.cmake do not get out of sync, which the current patch doesn't do. Cheers,