Yes for the sake of everything holy, the only time it's remotely acceptable to include with "" is for a header file corresponding to a source file. Otherwise always always include with <> and with the complete library prefix if possible, e.g. <SDL2/foo.h>, <libavcodec/codec.h>, etc etc and add as few include paths as you can, anything else is calling for subtle bugs if you're unlucky in how your third-party deps name their things