compile error

While trying make on the latest version of dillo3, I get the following:

g++ -I/usr/include/libpng12 -I/usr/include/freetype2 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_THREAD_SAFE -D_REENTRANT -g -O2 -Wall -W -Wno-unused-parameter -fno-rtti -fno-exceptions  -L/usr/local/lib -o dillo dillo.o paths.o ui.o uicmd.o bw.o cookies.o auth.o colors.o misc.o history.o prefs.o prefsparser.o keys.o url.o bitvec.o klist.o chain.o utf8.o timeout.o dialog.o web.o nav.o cache.o decode.o dicache.o capi.o css.o cssparser.o styleengine.o plain.o html.o form.o table.o bookmark.o dns.o gif.o jpeg.o png.o imgbuf.o image.o menu.o dpiapi.o findbar.o xembed.o ../dlib/libDlib.a ../dpip/libDpip.a IO/libDiof.a ../dw/libDw-widgets.a ../dw/libDw-fltk.a ../dw/libDw-core.a ../lout/liblout.a -L/usr/lib64 -lpng12 -lpng12 -lfltk -lz -lpthread 
/usr/bin/ld: xembed.o: undefined reference to symbol 'XSync'
/usr/bin/ld: note: 'XSync' is defined in DSO /usr/lib64/libX11.so.6 so try adding it to the linker command line
/usr/lib64/libX11.so.6: could not read symbols: Invalid operation
collect2: ld returned 1 exit status
make[3]: *** [dillo] Error 1


How does one fix this? 

Best!
T