I committed a safe fix for libpng-1.4, but it means that configure.in currently has: dnl Check if the user hasn't set the variable $PNG_CONFIG if test -z "$PNG_CONFIG"; then PNG_CONFIG=`which libpng14-config` if test -z "$PNG_CONFIG"; then PNG_CONFIG=`which libpng12-config` fi if test -z "$PNG_CONFIG"; then PNG_CONFIG=`which libpng-config` fi if test -z "$PNG_CONFIG"; then PNG_CONFIG=`which libpng10-config` fi fi and case $png_version in 1.4.*) AC_MSG_RESULT([$png_version (newer version)]) ;; 1.2.*) AC_MSG_RESULT([$png_version (newer version)]) ;; 1.0.*) AC_MSG_RESULT([$png_version (older version)]) ;; *) AC_MSG_RESULT([ERROR]) ;; esac I would strongly prefer to rip out most of that `which` stuff and just look for libpng-config. Does anyone know that this would be a bad idea? Whatever libpng-config is symlinked to is presumably what the user wants us to use...