diff --git a/ChangeLog b/ChangeLog
index a498778a7e..68eb368720 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sat Nov  5 19:11:50 2011  Tanaka Akira  <akr@fsij.org>
+
+	* io.c (rb_cloexec_fcntl_dupfd): don't clear try_dupfd_cloexec if
+	  fcntl(F_DUPFD) failed as fcntl(F_DUPFD_CLOEXEC).
+
 Sat Nov  5 18:05:12 2011  Tanaka Akira  <akr@fsij.org>
 
 	* ext/socket/socket.c (rsock_socketpair0): refactored.
diff --git a/io.c b/io.c
index 7a0bf4935c..8dabdbcc9a 100644
--- a/io.c
+++ b/io.c
@@ -297,8 +297,10 @@ rb_cloexec_fcntl_dupfd(int fd, int minfd)
         }
         /* F_DUPFD_CLOEXEC is available since Linux 2.6.24.  Linux 2.6.18 fails with EINVAL */
         if (errno == EINVAL) {
-            try_dupfd_cloexec = 0;
             ret = fcntl(fd, F_DUPFD, minfd);
+            if (ret != -1) {
+                try_dupfd_cloexec = 0;
+            }
         }
     }
     else {