Index: wp-includes/functions.php
===================================================================
--- wp-includes/functions.php	(revision 22995)
+++ wp-includes/functions.php	(working copy)
@@ -1540,7 +1540,9 @@
 
 			if ( defined( 'BLOGUPLOADDIR' ) )
 				$dir = untrailingslashit( BLOGUPLOADDIR );
-			$url = str_replace( untrailingslashit( UPLOADS ), 'files', $url );
+			else
+				$dir = ABSPATH . UPLOADS;
+			$url = trailingslashit( $siteurl ) . 'files';
 		}
 	}