diff --git a/ChangeLog b/ChangeLog
index b1c3aeaa8b..f50011dde0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sun Nov  8 15:19:17 2015  Masaki Matsushita <glass.saga@gmail.com>
+
+	* file.c: Add O_TMPFILE.
+
 Sun Nov  8 14:24:43 2015  windwiny  <windwiny.ubt@gmail.com>
 
 	* method.h (METHOD_ENTRY_{VISI,BASIC,FLAGS}_SET): suppress
diff --git a/file.c b/file.c
index e31b3eeadc..f45cfe6cdf 100644
--- a/file.c
+++ b/file.c
@@ -6082,6 +6082,10 @@ Init_File(void)
     /*  Try to minimize cache effects of the I/O to and from this file. */
     rb_define_const(rb_mFConst, "DIRECT", INT2FIX(O_DIRECT));
 #endif
+#ifdef O_TMPFILE
+    /* Create an unnamed temporary file */
+    rb_define_const(rb_mFConst, "TMPFILE", INT2FIX(O_TMPFILE));
+#endif
 
     /* shared lock. see File#flock */
     rb_define_const(rb_mFConst, "LOCK_SH", INT2FIX(LOCK_SH));