diff --git a/ChangeLog b/ChangeLog
index c5a668ff67..9e0f211c7a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sat Jul 20 15:02:51 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* safe.c (ruby_safe_level_4_warning): define for old extension
+	  libraries.  [Bug #8652]
+
 Sat Jul 20 14:38:00 2013  Koichi Sasada  <ko1@atdot.net>
 
 	* array.c (ary_make_shared): make shared array shady.
diff --git a/safe.c b/safe.c
index 030b473ddd..d9ded85b89 100644
--- a/safe.c
+++ b/safe.c
@@ -25,6 +25,13 @@
 
 #undef rb_secure
 #undef rb_set_safe_level
+#undef ruby_safe_level_4_warning
+
+int
+ruby_safe_level_4_warning(void)
+{
+    return 4;
+}
 
 int
 rb_safe_level(void)