diff --git a/ChangeLog b/ChangeLog
index 36c03a9a9d..c4ec1381f1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Sep 21 22:18:30 2010  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* tool/mkconfig.rb: fixed build problem on mswin64 introduced in r29278.
+
 Tue Sep 21 02:42:35 2010  Kazuhiro NISHIYAMA  <zn@mbf.nifty.com>
 
 	* test/pathname/test_pathname.rb (TestPathname#test_mkdir): fix typo.
diff --git a/tool/mkconfig.rb b/tool/mkconfig.rb
index d099eebeb9..160b6e5afe 100755
--- a/tool/mkconfig.rb
+++ b/tool/mkconfig.rb
@@ -35,7 +35,7 @@ module RbConfig
 ]
 
 arch = RUBY_PLATFORM
-win32 = /mswin32/ =~ arch
+win32 = /mswin/ =~ arch
 v_fast = []
 v_others = []
 vars = {}