diff --git a/ChangeLog b/ChangeLog
index ec0a19442d..e2b0562aa8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Oct 31 21:47:44 2011  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* io.c (rb_cloexec_pipe): NetBSD 6.0 will support pipe2(2),
+	  but its return value is -1 or larger than 0.
+
 Mon Oct 31 22:04:54 2011  Tanaka Akira  <akr@fsij.org>
 
 	* ext/dbm/dbm.c (fdbm_initialize): use O_CLOEXEC if available.
diff --git a/io.c b/io.c
index a87af126d8..cbbc2f8289 100644
--- a/io.c
+++ b/io.c
@@ -253,8 +253,14 @@ rb_cloexec_pipe(int fildes[2])
     static int try_pipe2 = 1;
     if (try_pipe2) {
         ret = pipe2(fildes, O_CLOEXEC);
+#ifdef defined(__NetBSD__)
+        /* pipe2 is available since NetBSD 6.0. */
+	if (ret > 0)
+	    return 0;
+#else
         if (ret != -1)
             return ret;
+#endif
         /* pipe2 is available since Linux 2.6.27. */
         if (errno == ENOSYS) {
             try_pipe2 = 0;