can't build gtk3: undefined reference to `gdk_x11_window_set_theme_variant'

[Tim Cuthbertson <tim gfxmonk net>]

./.libs/libgtk-3.so: undefined reference to `gdk_x11_window_set_theme_variant'
collect2: ld returned 1 exit status
linking of temporary binary failed: Command '['/bin/bash',
'../libtool', '--mode=link', '--tag=CC', '--silent', 'gcc', '-o',
'/home/tim/gnome-shell/source/gtk3/gtk/tmp-introspect8PS6yu/Gtk-3.0',
'-export-dynamic', '-L.', 'libgtk-3.la', '-pthread',
'-L/home/tim/gnome-shell/install/lib64', '-lgio-2.0', '-lgobject-2.0',
'-lgmodule-2.0', '-lgthread-2.0', '-lrt', '-lglib-2.0',
'/home/tim/gnome-shell/source/gtk3/gtk/tmp-introspect8PS6yu/Gtk-3.0.o']'
returned non-zero exit status 1
make[4]: *** [Gtk-3.0.gir] Error 1
make[4]: Leaving directory `/home/tim/gnome-shell/source/gtk3/gtk'
make[3]: *** [all-recursive] Error 1
make[3]: Leaving directory `/home/tim/gnome-shell/source/gtk3/gtk'
make[2]: *** [all] Error 2
make[2]: Leaving directory `/home/tim/gnome-shell/source/gtk3/gtk'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/home/tim/gnome-shell/source/gtk3'
make: *** [all] Error 2
*** Error during phase build of gtk3: ########## Error running make   *** [8/41]

Any ideas? I've done a jhbuild -afc build, same results. It seems like
every time I try and build gnome-shell, I get a different build error
:/