base64_encode, forward slashes and mod_rewrite

Continueing on my prior problem, Ive discovered that base64_encode adds forward slashes in its encoded string, when its urlencoded it becomes something like /feeds/UmFuZG9tSVZd%2FMChU7sMQqdUi%2FrgYHD7 mod_rewrite doesnt seem to like the %2F in the string and fails with a 404 as it doesnt get a match using RewriteRule ^feeds/(.*)$ /refer.php?$1 [L,NE] What should i do ? Should i replace the / with a different character then convert it back later ?