diff --git a/ChangeLog b/ChangeLog
index ce2a2d4500..a4e7d74659 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Oct 27 23:14:14 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* defs/id.def: enable anonymous IDs not to expose internal IDs for
+	  frozen-string-literal-debug by Marshal.dump.
+
 Tue Oct 27 17:06:55 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* defs/id.def: move internal IDs for frozen-string-literal-debug.
diff --git a/defs/id.def b/defs/id.def
index b63d1289b4..f79e5ef4cf 100644
--- a/defs/id.def
+++ b/defs/id.def
@@ -61,8 +61,8 @@ firstline, predefined = __LINE__+1, %[\
   core#hash_merge_ptr
   core#hash_merge_kwd
 
-  debug#created_path
-  debug#created_line
+  -                                                     debug#created_path
+  -                                                     debug#created_line
 ]
 
 class KeywordError < RuntimeError
@@ -95,6 +95,10 @@ predefined.split(/^/).each_with_index do |line, num|
     token.sub!(/\A@/, "_I_")
     token.gsub!(/\W+/, "")
   end
+  if name == '-'
+    preserved_ids << token
+    next
+  end
   if prev = names[name]
     KeywordError.raise("#{name} is already registered at line #{prev+firstline}", firstline+num)
   end