--- lib/mkmf.rb.orig	2008-08-23 12:40:10.000000000 +0700
+++ lib/mkmf.rb	2008-08-23 12:40:23.000000000 +0700
@@ -18,7 +18,7 @@
 
 unless defined? $configure_args
   $configure_args = {}
-  args = CONFIG["configure_args"]
+  args = CONFIG["configure_args"] || ""
   if ENV["CONFIGURE_ARGS"]
     args << " " << ENV["CONFIGURE_ARGS"]
   end