diff --git a/mod/assign/renderer.php b/mod/assign/renderer.php
index eea7fac2a25..05d0c8df6f6 100644
--- a/mod/assign/renderer.php
+++ b/mod/assign/renderer.php
@@ -164,7 +164,7 @@ class mod_assign_renderer extends plugin_renderer_base {
             $fullname = fullname($summary->user, $summary->viewfullnames);
             $extrainfo = array();
             foreach ($summary->extrauserfields as $extrafield) {
-                $extrainfo[] = $summary->user->$extrafield;
+                $extrainfo[] = s($summary->user->$extrafield);
             }
             if (count($extrainfo)) {
                 $fullname .= ' (' . implode(', ', $extrainfo) . ')';