***************
*** 20,23 ****
    fi
    AC_DEFINE(HAVE_WDDX, 1, [ ])
    PHP_NEW_EXTENSION(wddx, wddx.c, $ext_shared)
  fi
--- 23,31 ----
    fi
    AC_DEFINE(HAVE_WDDX, 1, [ ])
    PHP_NEW_EXTENSION(wddx, wddx.c, $ext_shared)
+ 
+   PHP_SETUP_LIBXML(WDDX_SHARED_LIBADD, [
+   ], [
+     AC_MSG_ERROR([xml2-config not found. Please check your libxml2 installation.])
+   ])
  fi