Index: lxpanel-0.5.9/configure.ac
===================================================================
--- lxpanel-0.5.9.orig/configure.ac
+++ lxpanel-0.5.9/configure.ac
@@ -79,7 +79,7 @@ PKG_CHECK_MODULES(X11, [$pkg_modules])
 AC_SUBST(X11_LIBS)
 
 pkg_modules="libwnck-1.0"
-PKG_CHECK_MODULES(WNCK, [$pkg_modules])
+PKG_CHECK_MODULES(WNCK, [$pkg_modules], [:], [:])
 AC_SUBST(WNCK_CFLAGS)
 AC_SUBST(WNCK_LIBS)