diff --git a/ChangeLog b/ChangeLog
index 33fe6dc92c..aee1f38f5f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Fri Oct 23 00:49:45 2015  Shugo Maeda  <shugo@ruby-lang.org>
+
+	* lib/un.rb (help): change the name of a block parameter to avoid
+	  a warning when the command line option -w of ruby is specified.
+
 Fri Oct 23 00:22:20 2015  Josef Simanek  <josef.simanek@gmail.com>
 
 	* string.c (rb_str_tr): [DOC] Escape backslash in String#tr
diff --git a/lib/un.rb b/lib/un.rb
index ac1abe8d8b..1f336a4442 100644
--- a/lib/un.rb
+++ b/lib/un.rb
@@ -367,7 +367,7 @@ module UN # :nodoc:
       end
     end
     if messages
-      argv.each {|cmd| output << messages[cmd]}
+      argv.each {|arg| output << messages[arg]}
     end
   end
 end