I use MinGW (first party MinGW, not the third party MinGW-64) exclusively, but then again I don't put spaces in my project paths because I don't want to have to troubleshoot any problems that may come of it. If you remove the $(PROJECT_DIR) variable and explicitly define the path with quotation marks, does it work? If not, then this isn't a problem C::B can solve because the compiler isn't allowing you to use the path containing spaces.