diff --git a/ChangeLog b/ChangeLog
index 67e03f9a60..e3680c3ad0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun Mar  6 03:22:27 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+
+	* io.c (io_cntl): use rb_thread_io_blocking_region() instead
+	  rb_thread_blocking_region().
+
 Sat Mar  5 22:54:36 2011  CHIKANAGA Tomoyuki  <nagachika00@gmail.com>
 
 	* include/ruby/intern.h: fix a typo of prototype declaration.
diff --git a/io.c b/io.c
index 055262aa34..064d1a2eef 100644
--- a/io.c
+++ b/io.c
@@ -7683,7 +7683,7 @@ io_cntl(int fd, int cmd, long narg, int io_p)
     arg.narg = narg;
     arg.io_p = io_p;
 
-    retval = (int)rb_thread_blocking_region(nogvl_io_cntl, &arg, RUBY_UBF_IO, 0);
+    retval = (int)rb_thread_io_blocking_region(nogvl_io_cntl, &arg, fd);
 #if defined(F_DUPFD)
     if (!io_p && retval != -1 && cmd == F_DUPFD) {
 	UPDATE_MAXFD(retval);