diff --git a/ChangeLog b/ChangeLog
index 5d8b46c31d..acee9ae225 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun Mar  1 11:17:56 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* gc.c (id2ref): prohibit from accessing internal objects.
+	  [ruby-core:68348] [Bug #10918]
+
 Sun Mar  1 09:06:11 2015  Tanaka Akira  <akr@fsij.org>
 
 	* lib/time.rb (strptime): Support %s.%N.
diff --git a/gc.c b/gc.c
index c84da503ea..b843e7bb73 100644
--- a/gc.c
+++ b/gc.c
@@ -2761,6 +2761,9 @@ 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;
 }