--- a/lib/mkmf.rb	2009-06-10 09:09:22.000000000 +0200
+++ b/lib/mkmf.rb	2011-11-12 02:53:05.862766935 +0100
@@ -168,19 +168,25 @@
 module Logging
   @log = nil
   @logfile = 'mkmf.log'
-  @orgerr = $stderr.dup
-  @orgout = $stdout.dup
   @postpone = 0
 
   def self::open
     @log ||= File::open(@logfile, 'w')
     @log.sync = true
+    orgerr = $stderr.dup
+    orgout = $stdout.dup
     $stderr.reopen(@log)
     $stdout.reopen(@log)
     yield
   ensure
-    $stderr.reopen(@orgerr)
-    $stdout.reopen(@orgout)
+    if orgerr
+      $stderr.reopen(orgerr)
+      orgerr.close
+    end
+    if orgout
+      $stdout.reopen(orgout)
+      orgout.close
+    end
   end
 
   def self::message(*s)