diff --git a/ChangeLog b/ChangeLog
index 272150d919..4f4ab35b89 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Mon Jan 31 21:57:39 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+
+	* configure.in: revert r30698.
+
 Mon Jan 31 21:32:44 2011  CHIKANAGA Tomoyuki  <nagachika00@gmail.com>
 
 	* thread.c (thread_start_func_2): check deadlock condition before
diff --git a/configure.in b/configure.in
index 426fce5502..545bd7037c 100644
--- a/configure.in
+++ b/configure.in
@@ -659,9 +659,9 @@ AC_DEFUN([RUBY_REPLACE_TYPE], [dnl
 			[typedef $n rbcv_conftest_target_type;
 			typedef $t rbcv_conftest_replace_type;
 			extern rbcv_conftest_target_type rbcv_conftest_var;
-			extern rbcv_conftest_replace_type rbcv_conftest_var2;
+			extern rbcv_conftest_replace_type rbcv_conftest_var;
 			extern rbcv_conftest_target_type rbcv_conftest_func(void);
-			extern rbcv_conftest_replace_type rbcv_conftest_func2(void);
+			extern rbcv_conftest_replace_type rbcv_conftest_func(void);
 			], [sizeof(rbcv_conftest_target_type) == sizeof(rbcv_conftest_replace_type)])],
 		    [n="$t"; break])
 	    done