diff --git a/ChangeLog b/ChangeLog
index 8b1be1c5a9..4c7f624f7f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu May 21 09:49:01 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* gc.c (id2ref): prohibit from accessing internal objects.
+	  [ruby-core:68348] [Bug #10918]
+
 Thu May 21 09:46:58 2015  Rei Odaira  <Rei.Odaira@gmail.com>
 
 	* ext/pty/pty.c: AIX supports autopush.
diff --git a/gc.c b/gc.c
index f9048e031a..785a50d0ea 100644
--- a/gc.c
+++ b/gc.c
@@ -2332,6 +2332,9 @@ id2ref(VALUE obj, VALUE objid)
     if (!is_live_object(objspace, ptr)) {
 	rb_raise(rb_eRangeError, "%p is recycled object", p0);
     }
+    if (RBASIC(ptr)->klass == 0) {
+	rb_raise(rb_eRangeError, "%p is internal object", p0);
+    }
     return (VALUE)ptr;
 }
 
diff --git a/version.h b/version.h
index e9e6afe790..4fc99cfb49 100644
--- a/version.h
+++ b/version.h
@@ -1,6 +1,6 @@
 #define RUBY_VERSION "2.1.7"
 #define RUBY_RELEASE_DATE "2015-05-21"
-#define RUBY_PATCHLEVEL 346
+#define RUBY_PATCHLEVEL 347
 
 #define RUBY_RELEASE_YEAR 2015
 #define RUBY_RELEASE_MONTH 5