diff --git a/ChangeLog b/ChangeLog
index e7a0bd348a..46d4a9eea9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Mar 11 11:53:35 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/mkmf.rb (MakeMakefile#dir_config, MakeMakefile#_libdir_basename):
+	  defer use of instance variable until needed.  [Bug #8074]
+
 Thu Mar  7 10:42:28 2013  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* lib/thread.rb (Queue#clear): return self.
diff --git a/lib/mkmf.rb b/lib/mkmf.rb
index fc12465123..e208515e8a 100644
--- a/lib/mkmf.rb
+++ b/lib/mkmf.rb
@@ -45,6 +45,16 @@ end
 # correctly compile and link the C extension to ruby and a third-party
 # library.
 module MakeMakefile
+  #### defer until this module become global-state free.
+  # def self.extended(obj)
+  #   obj.init_mkmf
+  #   super
+  # end
+  #
+  # def initialize(*args, rbconfig: RbConfig, **rest)
+  #   init_mkmf(rbconfig::MAKEFILE_CONFIG, rbconfig::CONFIG)
+  #   super(*args, **rest)
+  # end
 
   ##
   # The makefile configuration using the defaults from when ruby was built.
@@ -1676,7 +1686,7 @@ SRC
     idir = with_config(target + "-include", idefault)
     $arg_config.last[1] ||= "${#{target}-dir}/include"
     ldir = with_config(target + "-lib", ldefault)
-    $arg_config.last[1] ||= "${#{target}-dir}/#{@libdir_basename}"
+    $arg_config.last[1] ||= "${#{target}-dir}/#{_libdir_basename}"
 
     idirs = idir ? Array === idir ? idir.dup : idir.split(File::PATH_SEPARATOR) : []
     if defaults
@@ -1693,7 +1703,7 @@ SRC
 
     ldirs = ldir ? Array === ldir ? ldir.dup : ldir.split(File::PATH_SEPARATOR) : []
     if defaults
-      ldirs.concat(defaults.collect {|d| "#{d}/#{@libdir_basename}"})
+      ldirs.concat(defaults.collect {|d| "#{d}/#{_libdir_basename}"})
       ldir = ([ldir] + ldirs).compact.join(File::PATH_SEPARATOR)
     end
     $LIBPATH = ldirs | $LIBPATH
@@ -2378,8 +2388,6 @@ site-install-rb: install-rb
     $extout ||= nil
     $extout_prefix ||= nil
 
-    @libdir_basename = config["libdir"] && config["libdir"][/\A\$\(exec_prefix\)\/(.*)/, 1] or "lib"
-
     $arg_config.clear
     dir_config("opt")
   end
@@ -2404,6 +2412,12 @@ MESSAGE
     end
   end
 
+  private
+
+  def _libdir_basename
+    @libdir_basename ||= config_string("libdir") {|name| name[/\A\$\(exec_prefix\)\/(.*)/, 1]} || "lib"
+  end
+
   extend self
   init_mkmf
 
diff --git a/test/mkmf/test_config.rb b/test/mkmf/test_config.rb
new file mode 100644
index 0000000000..c0b2355ee1
--- /dev/null
+++ b/test/mkmf/test_config.rb
@@ -0,0 +1,14 @@
+require 'test/unit'
+require 'mkmf'
+require_relative '../ruby/envutil'
+
+class TestMkmf
+  class TestConfig < Test::Unit::TestCase
+    def test_dir_config
+      bug8074 = '[Bug #8074]'
+      assert_separately %w[-rmkmf - -- --with-foo-dir=/test/foo], %{
+        assert_equal(%w[/test/foo/include /test/foo/lib], dir_config("foo"), #{bug8074.dump})
+      }
+    end
+  end
+end