The include directory in gnuradio-osmosdr.pc.in includedir=${prefix}/@GR_INCLUDE_DIR@ ends up pointing to includedir=${prefix}/include when the file gnuradio-osmosdr.pc is installed in $prefix/lib/pkgconfig. But it appears the include files for gnuradio-osmosdr.pc are installed in includedir=${prefix}/include/osmosdr When I attempted to build software using gr-osmosdr outside of the gnuradio tree, I had to add the subdirectory ./osmosdr to the include path in gnuradio-osmosdr.pc otherwise cmake complained it couldn't find the gnuradio-osmosdr includes. Since it appears to build gr-osmosdr without the subdirectory osmosdr added to the include path, I'm not really sure what's going on. -- Cinaed