diff --git a/ChangeLog b/ChangeLog
index d169fe4c7c..488d797c0e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu May  5 10:49:33 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* random.c (fill_random_bytes_syscall): use arc4random_buf if
+	  available.
+
 Wed May  4 23:13:58 2016  Yuichiro Kaneko  <yui-knk@ruby-lang.org>
 
 	* numeric.c (fix_plus): Remove rb_nucomp_add prototype
diff --git a/configure.in b/configure.in
index 43af2bdced..d24619e9a0 100644
--- a/configure.in
+++ b/configure.in
@@ -2270,6 +2270,7 @@ AC_CHECK_FUNCS(_longjmp)		# used for AC_ARG_WITH(setjmp-type)
 test x$ac_cv_func__longjmp = xno && ac_cv_func__setjmp=no
 AC_CHECK_FUNCS(_setjmp)			# used for AC_ARG_WITH(setjmp-type)
 AC_CHECK_FUNCS(_setjmpex)		# used for AC_ARG_WITH(setjmp-type)
+AC_CHECK_FUNCS(arc4random_buf)
 AC_CHECK_FUNCS(atan2l atan2f)
 AC_CHECK_FUNCS(chroot)
 AC_CHECK_FUNCS(chsize)
diff --git a/random.c b/random.c
index 06c66ca721..31e7db22f4 100644
--- a/random.c
+++ b/random.c
@@ -480,7 +480,10 @@ fill_random_bytes_urandom(void *seed, size_t size)
 # define fill_random_bytes_urandom(seed, size) -1
 #endif
 
-#if defined(_WIN32)
+#if 0
+#elif defined(HAVE_ARC4RANDOM_BUF)
+#define fill_random_bytes_syscall(buf, size, unused) (arc4random_buf(buf, size), 0)
+#elif defined(_WIN32)
 static void
 release_crypt(void *p)
 {