diff --git a/ChangeLog b/ChangeLog
index cd2ccdbf7e..c1cf0c714c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sat Oct 29 20:59:08 2011  Tanaka Akira  <akr@fsij.org>
+
+	* io.c (rb_cloexec_dup): use F_DUPFD_CLOEXEC if available.
+
 Sat Oct 29 20:00:26 2011  Tanaka Akira  <akr@fsij.org>
 
 	* include/ruby/intern.h (rb_cloexec_dup): declared.
diff --git a/io.c b/io.c
index bde6ff4a36..fad64cafe8 100644
--- a/io.c
+++ b/io.c
@@ -205,7 +205,23 @@ int
 rb_cloexec_dup(int oldfd)
 {
     int ret;
+
+#ifdef F_DUPFD_CLOEXEC
+    static int try_fcntl = 1;
+    if (try_fcntl) {
+        ret = fcntl(oldfd, F_DUPFD_CLOEXEC, 0);
+        /* F_DUPFD_CLOEXEC is available since Linux 2.6.24.  Linux 2.6.18 fails with EINVAL */
+        if (ret == -1 && errno == EINVAL) {
+            try_fcntl = 0;
+            ret = dup(oldfd);
+        }
+    }
+    else {
+        ret = dup(oldfd);
+    }
+#else
     ret = dup(oldfd);
+#endif
     if (ret == -1) return -1;
     fd_set_cloexec(ret);
     return ret;