CDR customized PHP pages being overwritten

FreePBX 2.9.0.11/Asterisk 1.8.3.3

Edited .php files in /var/www/html/admin/cdr (call-log.php, call-comp.php, etc.) in order to add userfield & other items to the Reports page.

My edits get overwritten with module upgrades. Any way to prevent this from happening so I don’t have to go back and reload the edited versions every time?

Not critical, but it bites me everytime I do a module upgrade and forget to replace the FPBX files with my edited versions…