diff --git a/view.php b/view.php
index 1a62e6f..246c6f2 100644
--- a/view.php
+++ b/view.php
@@ -27,6 +27,7 @@
 require_once('../../config.php');
 require_once($CFG->dirroot . '/mod/customcert/lib.php');
 require_once($CFG->libdir . '/pdflib.php');
+require_once($CFG->dirroot . '/mod/customcert/includes/tcpdf_colors.php');
 
 $id = required_param('id', PARAM_INT);
 $action = optional_param('action', '', PARAM_ALPHA);