diff --git a/mod/glossary/showentry.php b/mod/glossary/showentry.php
index b1987211b77..4d9acafc113 100644
--- a/mod/glossary/showentry.php
+++ b/mod/glossary/showentry.php
@@ -5,7 +5,7 @@
     $concept  = optional_param('concept', '', PARAM_CLEAN);
     $courseid = optional_param('courseid', 0, PARAM_INT);
     $eid      = optional_param('eid', 0, PARAM_INT); // glossary entry id
-    $displayformat = optional_param('displayformat',-1, PARAM_INT);
+    $displayformat = optional_param('displayformat',-1, PARAM_SAFEDIR);
 
     if ($CFG->forcelogin) {
         require_login();