diff --git a/filter/activitynames/filter.php b/filter/activitynames/filter.php
index edd7d3f40bad4..38af76c35a99e 100644
--- a/filter/activitynames/filter.php
+++ b/filter/activitynames/filter.php
@@ -15,10 +15,11 @@ function activitynames_filter($courseid, $text) {
         $course = get_record("course","id",$courseid);
         $modinfo = unserialize($course->modinfo);
 
-        //Sort modinfo by name length
-        usort($modinfo,'comparemodulenamesbylength');
-
         if (!empty($modinfo)) {
+
+            //Sort modinfo by name length
+            usort($modinfo,'comparemodulenamesbylength');
+
             $cm = '';
             foreach ($modinfo as $activity) {
                 //Exclude labels and hidden items