diff --git a/ChangeLog b/ChangeLog
index e39be29d68..0aab11a410 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Dec 15 19:07:31 2008  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* win32/Makefile.sub (config.h): define CANONICALIZATION_FOR_MATHN
+	  to follow r20683.
+
 Mon Dec 15 18:12:34 2008  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* lib/rake/packagetask.rb (Rake::PackageTask): small document
diff --git a/win32/Makefile.sub b/win32/Makefile.sub
index 20763633dd..862230785d 100644
--- a/win32/Makefile.sub
+++ b/win32/Makefile.sub
@@ -461,6 +461,7 @@ $(CONFIG_H): $(MKFILES) $(srcdir)/win32/Makefile.sub $(win_srcdir)/Makefile.sub
 !if "$(PROCESSOR_ARCHITECTURE)" == "x86" || "$(ARCH)" == "x64" || "$(ARCH)" == "ia64"
 #define STACK_GROW_DIRECTION -1
 !endif
+#define CANONICALIZATION_FOR_MATHN 1
 #define DEFAULT_KCODE KCODE_NONE
 #define DLEXT ".so"
 #define RUBY_LIB "/lib/$(RUBY_INSTALL_NAME)/$(ruby_version)"