diff --git a/ChangeLog b/ChangeLog
index 4c7203ad6a..4be5ac6361 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Wed Aug 31 00:48:38 2011  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* thread.c (rb_thread_select): critical typo in r33117.
+
 Wed Aug 31 00:30:49 2011  NAKAMURA Usaku  <usa@ruby-lang.org>
 
 	* test/-ext-/old_thread_select/test_old_thread_select.rb
diff --git a/thread.c b/thread.c
index a09c39eed4..16e890656b 100644
--- a/thread.c
+++ b/thread.c
@@ -2708,7 +2708,7 @@ rb_thread_select(int max, fd_set * read, fd_set * write, fd_set * except,
 	rb_fd_copy(efds, except, max);
     }
 
-    retval = rb_thread_fd_select(max, rfds, efds, wfds, timeout);
+    retval = rb_thread_fd_select(max, rfds, wfds, efds, timeout);
 
     if (rfds)
 	rb_fd_term(rfds);