Re: [Libguestfs] Error building nbdkit on RHEL 7.5 - possibly undefined macro: PKG_CHECK_VAR

I'm trying to build upstream source on RHEL 7.5 and get this error: # autoreconf -i libtoolize: putting auxiliary files in `.'. libtoolize: copying file `./ltmain.sh' libtoolize: putting macros in AC_CONFIG_MACRO_DIR, `m4'. libtoolize: copying file `m4/libtool.m4' libtoolize: copying file `m4/ltoptions.m4' libtoolize: copying file `m4/ltsugar.m4' libtoolize: copying file `m4/ltversion.m4' libtoolize: copying file `m4/lt~obsolete.m4' configure.ac:190: error: possibly undefined macro: PKG_CHECK_VAR If this token and others are legitimate, please use m4_pattern_allow. See the Autoconf documentation. autoreconf: /usr/bin/autoconf failed with exit status: 1 How to fix this? I hope I can avoid reading autoconf documentation :-)