diff -ruN ruby-1.8.5-p12.orig/configure.in ruby-1.8.5-p12/configure.in
--- ruby-1.8.5-p12.orig/configure.in	2006-12-06 19:58:08.000000000 +0900
+++ ruby-1.8.5-p12/configure.in	2007-02-05 17:02:43.000000000 +0900
@@ -1505,6 +1505,13 @@
     rubyw_install_name="$RUBYW_INSTALL_NAME"
     ;;
 esac
+
+AC_ARG_WITH(ruby-prefix,
+	AC_HELP_STRING([--with-ruby-prefix], [build ruby with the special library prefix.])
+	,,
+	with_ruby_prefix=no)
+
+if test "x$with_ruby_prefix" = "x"; then
 case "$target_os" in
   cygwin*|mingw*|*djgpp*|os2-emx*)
     RUBY_LIB_PREFIX="/lib/ruby"
@@ -1513,20 +1520,29 @@
     RUBY_LIB_PREFIX="${prefix}/lib/ruby"
     ;;
 esac
+else
+	RUBY_LIB_PREFIX="${with_ruby_prefix}/ruby"
+fi
 RUBY_LIB_PATH="${RUBY_LIB_PREFIX}/${MAJOR}.${MINOR}"
+RUBY_LIB_PATH2="${libdir}/ruby/${MAJOR}.${MINOR}"
 
 AC_ARG_WITH(sitedir,
 	    [  --with-sitedir=DIR      site libraries in DIR [PREFIX/lib/ruby/site_ruby]],
             [sitedir=$withval],
             [sitedir='${prefix}/lib/ruby/site_ruby'])
-SITE_DIR=`eval echo \\"${sitedir}\\"`
+SITE_DIR=`eval echo \\"${sitedir}\\" | sed -e "s/lib64/lib/"`
+_fc_sitedir="\$(DESTDIR)${sitedir}"
+SITE_DIR2=`eval echo \\"${_fc_sitedir}\\"`
+sitedir=`eval echo \\"${sitedir}\\" | sed -e "s/lib64/lib/"`
 case "$target_os" in
   cygwin*|mingw*|*djgpp*|os2-emx*)
     RUBY_SITE_LIB_PATH="`expr "$SITE_DIR" : "$prefix\(/.*\)"`" ||
     RUBY_SITE_LIB_PATH="$SITE_DIR";;
   *)
-    RUBY_SITE_LIB_PATH="$SITE_DIR";;
+    RUBY_SITE_LIB_PATH="$SITE_DIR";
+    RUBY_SITE_LIB_PATH2="$SITE_DIR2";;
 esac
+RUBY_SITE_LIB_PATH3="${RUBY_SITE_LIB_PATH2}/${MAJOR}.${MINOR}"
 RUBY_SITE_LIB_PATH2="${RUBY_SITE_LIB_PATH}/${MAJOR}.${MINOR}"
 
 AC_DEFINE_UNQUOTED(RUBY_LIB, "${RUBY_LIB_PATH}")
@@ -1536,6 +1552,7 @@
 AC_SUBST(arch)dnl
 AC_SUBST(sitearch)dnl
 AC_SUBST(sitedir)dnl
+AC_SUBST(_fc_sitedir)dnl
 
 configure_args=$ac_configure_args
 AC_SUBST(configure_args)dnl
@@ -1544,7 +1561,7 @@
     arch="fat-${target_os}"
 
     AC_DEFINE_UNQUOTED(RUBY_THIN_ARCHLIB,
-                 "${RUBY_LIB_PATH}/" __ARCHITECTURE__ "-${target_os}")
+                 "${RUBY_LIB_PATH2}/" __ARCHITECTURE__ "-${target_os}")
 
     AC_DEFINE_UNQUOTED(RUBY_SITE_THIN_ARCHLIB,
                  "${RUBY_SITE_LIB_PATH}/" __ARCHITECTURE__ "-${target_os}")
@@ -1559,8 +1576,8 @@
   *) sitearch="${arch}" ;;
 esac
 
-AC_DEFINE_UNQUOTED(RUBY_ARCHLIB, "${RUBY_LIB_PATH}/${arch}")
-AC_DEFINE_UNQUOTED(RUBY_SITE_ARCHLIB, "${RUBY_SITE_LIB_PATH2}/${sitearch}")
+AC_DEFINE_UNQUOTED(RUBY_ARCHLIB, "${RUBY_LIB_PATH2}/${arch}")
+AC_DEFINE_UNQUOTED(RUBY_SITE_ARCHLIB, "${RUBY_SITE_LIB_PATH3}/${sitearch}")
 
 AC_ARG_WITH(search-path,
 		[  --with-search-path=DIR specify the additional search path],
diff -ruN ruby-1.8.5-p12.orig/mkconfig.rb ruby-1.8.5-p12/mkconfig.rb
--- ruby-1.8.5-p12.orig/mkconfig.rb	2006-06-25 23:03:10.000000000 +0900
+++ ruby-1.8.5-p12/mkconfig.rb	2007-02-05 16:54:32.000000000 +0900
@@ -108,10 +108,10 @@
 print v_fast, v_others
 print <<EOS
   CONFIG["ruby_version"] = "$(MAJOR).$(MINOR)"
-  CONFIG["rubylibdir"] = "$(libdir)/ruby/$(ruby_version)"
-  CONFIG["archdir"] = "$(rubylibdir)/$(arch)"
+  CONFIG["rubylibdir"] = "$(prefix)/lib/ruby/$(ruby_version)"
+  CONFIG["archdir"] = "$(libdir)/ruby/$(ruby_version)/$(arch)"
   CONFIG["sitelibdir"] = "$(sitedir)/$(ruby_version)"
-  CONFIG["sitearchdir"] = "$(sitelibdir)/$(sitearch)"
+  CONFIG["sitearchdir"] = "$(_fc_sitedir)/$(ruby_version)/$(sitearch)"
   CONFIG["topdir"] = File.dirname(__FILE__)
   MAKEFILE_CONFIG = {}
   CONFIG.each{|k,v| MAKEFILE_CONFIG[k] = v.dup}