1 files changed, 9 insertions, 1 deletions
diff --git a/mkconfig.rb b/mkconfig.rb
index 671e9bdbe8..2e346c15af 100644
--- a/mkconfig.rb
+++ b/mkconfig.rb
@@ -20,7 +20,7 @@ module Config
 # made to this file will be lost the next time ruby is built.
 ]
 
-print "  CONFIG = {}\n"
+print "  DESTDIR = '' if not defined? DESTDIR\n  CONFIG = {}\n"
 v_fast = []
 v_others = []
 has_version = false
@@ -72,6 +72,14 @@ if not has_version
   }
 end
 
+v_fast.collect! do |x|
+  if /"prefix"/ === x
+    x.sub(/= /, '= DESTDIR + ')
+  else
+    x
+  end
+end
+
 print v_fast, v_others
 print <<EOS
   CONFIG["compile_dir"] = "#{Dir.pwd}"