Index: wp-includes/functions.php
===================================================================
--- wp-includes/functions.php	(revision 22613)
+++ wp-includes/functions.php	(working copy)
@@ -1540,7 +1540,7 @@
 
 			if ( defined( 'BLOGUPLOADDIR' ) )
 				$dir = untrailingslashit( BLOGUPLOADDIR );
-			$url = str_replace( UPLOADS, 'files', $url );
+			$url = str_replace( untrailingslashit(UPLOADS), 'files', $url );
 		}
 	}