AC_CHECK_LIB(pthread, main, [pthread=true], [pthread=false])
if test "$zlib" = "true" ; then
- AC_CHECK_LIB(png, main, [png=true ; AC_DEFINE(HAVE_PNG,1,[PNG library])], [png=false])
+ AC_CHECK_LIB(png, main, [png=true ; AC_DEFINE(HAVE_PNG,1,[PNG library])], [png=false], [-lz -lm])
fi
dnl Checks for header files.