qjackctl right now is building with hard dependency on X11, for uniqueness checking. Because of this dep, it cannot be started natively on Wayland using "-platform wayland". This could be easily disabled by adding $(use_enable X xunique) into the ebuild.The re-emerging qjackctl with USE="-X" fixes segfault in qjackctl. Also, it seems that it depends on X11: AC_CHECK_LIB(m, main) AC_CHECK_LIB(X11, main) AC_CHECK_LIB(Xext, main) .... # Some recent distros (eg. fedora, debian) require this. ac_libs="$ac_libs -lX11" This should be also optional, I think, or it should be reflected in the RDEPEND/DEPEND section, at least.