diff --git a/ChangeLog b/ChangeLog
index ac33ac8fcd..5a1fdcc27d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Thu Jul 22 20:58:55 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* configure.in (RUBY_EXTERN): unnecessary after all.
+
 Thu Jul 22 20:12:56 2010  Yusuke Endoh  <mame@tsg.ne.jp>
 
 	* thread_pthread.c (get_stack): fix memory leak; pthread_attr_destory
diff --git a/configure.in b/configure.in
index 7c43cab170..bf7fdb6929 100644
--- a/configure.in
+++ b/configure.in
@@ -269,7 +269,6 @@ if test "$GCC" = yes; then
     linker_flag=-Wl,
     : ${optflags=-O3}
     AS_CASE(["$target_os"], [linux*|darwin*], [: ${debugflags=-ggdb}])
-    RUBY_APPEND_OPTIONS(XCFLAGS, ["-include ruby/config.h" "-include ruby/missing.h"])
 else
     linker_flag=
 fi
@@ -748,18 +747,6 @@ if test "$GCC" = yes; then
     fi
 fi
 
-AC_CACHE_CHECK([for RUBY_EXTERN], rb_cv_ruby_extern,
-[rb_cv_ruby_extern=no
-RUBY_WERROR_FLAG([
-for mac in "__attribute__((dllimport))" "__declspec(dllimport)"; do
-  AC_TRY_COMPILE(
-    [extern $mac void conftest(void);],
-    [conftest();],
-    [rb_cv_ruby_extern="extern $mac"; break])
-done])
-])
-test "x$rb_cv_ruby_extern" = xno || AC_DEFINE_UNQUOTED(RUBY_EXTERN, $rb_cv_ruby_extern)
-
 RUBY_APPEND_OPTION(XCFLAGS, -DRUBY_EXPORT)
 
 dnl }