diff --git a/lib/moodlelib.php b/lib/moodlelib.php
index 472c4aeb0b69d..36377c6120a6f 100644
--- a/lib/moodlelib.php
+++ b/lib/moodlelib.php
@@ -484,7 +484,7 @@ function clean_param($param, $type) {
             return $param;
 
         case PARAM_LOCALURL:     // allow http absolute, root relative and relative URLs within wwwroot
-            clean_param($param, PARAM_URL);
+            $param = clean_param($param, PARAM_URL);
             if (!empty($param)) {
                 if (preg_match(':^/:', $param)) {
                     // root-relative, ok!