Make all WordPress URLs lowercase

I'm trying to to get all my WordPress urls to be lowercase, but the following code doesn't seem to be working...

RewriteEngine On
RewriteBase /

RewriteMap tolower int:tolower
RewriteCond $1 [A-Z]
RewriteRule ^/(.*)$ /${tolower:$1} [R=301]

RewriteRule ^index\.php$ - [L]
开发者_StackOverflowRewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]

</IfModule>

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You can use the module mod_speling for PHP (you need to load it first) and the CheckCaseOnly on|off option in your .htaccess file.