--- lib/mkmf.rb.orig	2013-02-16 16:09:52.000000000 +0900
+++ lib/mkmf.rb	2013-02-16 20:42:14.000000000 +0900
@@ -2344,7 +2344,7 @@
     $LIBPATH = []
     $INSTALLFILES = []
     $NONINSTALLFILES = [/~\z/, /\A#.*#\z/, /\A\.#/, /\.bak\z/i, /\.orig\z/, /\.rej\z/, /\.l[ao]\z/, /\.o\z/]
-    $VPATH = %w[$(srcdir) $(topdir) $(arch_hdrdir)/ruby $(hdrdir)/ruby]
+    $VPATH = %w[$(srcdir) $(arch_hdrdir)/ruby $(hdrdir)/ruby]
 
     $objs = nil
     $srcs = nil