diff --git a/ChangeLog b/ChangeLog
index 636c4d7234..1d426a9c80 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon May 25 22:35:58 2015  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* tool/redmine-backporter.rb (rel): after the relations is changed,
+	  @changesets is no longer right.
+
 Mon May 25 11:27:14 2015  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* win32/win32.c (setup_overlapped): seek to the file end only when
diff --git a/tool/redmine-backporter.rb b/tool/redmine-backporter.rb
index 1b25cd3e4f..aa9991155c 100755
--- a/tool/redmine-backporter.rb
+++ b/tool/redmine-backporter.rb
@@ -408,6 +408,9 @@ eom
       res = http.post(uri.path, "issue_id=#@issue",
                      'X-Redmine-API-Key' => REDMINE_API_KEY)
       puts res.body
+      class << @changesets
+        remove_method(:validated) rescue nil
+      end
     end
   },