diff --git a/module/VuFindSearch/src/VuFindSearch/Backend/Primo/Connector.php b/module/VuFindSearch/src/VuFindSearch/Backend/Primo/Connector.php
index f30e229c9286025d16e7af8d8a418086f9a64a52..1f72077f7351c0b4b90efdaa96729440f16b2568 100644
--- a/module/VuFindSearch/src/VuFindSearch/Backend/Primo/Connector.php
+++ b/module/VuFindSearch/src/VuFindSearch/Backend/Primo/Connector.php
@@ -281,7 +281,7 @@ class Connector implements \Laminas\Log\LoggerAwareInterface
                         $facetOp = $values['facetOp'];
                         $values = $values['values'];
                     }
-                    array_map(
+                    $values = array_map(
                         function ($value) {
                             return urlencode(preg_replace('/,/', '+', $value));
                         },