diff --git a/src/Plugin/facets/widget/MultiselectCheckboxWidget.php b/src/Plugin/facets/widget/MultiselectCheckboxWidget.php
index b5d806e0..131308ac 100644
--- a/src/Plugin/facets/widget/MultiselectCheckboxWidget.php
+++ b/src/Plugin/facets/widget/MultiselectCheckboxWidget.php
@@ -82,10 +82,11 @@ public function build(FacetInterface $facet) {
    * {@inheritdoc}
    */
   public function prepareValueForUrl(FacetInterface $facet, array &$form, FormStateInterface $form_state): array {
-    $values = $form_state->getValue($facet->id());
-    // Remove "0" values, unchecked checkboxes.
-    $values = array_filter($values);
-    return $values;
+    $values = array_filter($form_state->getValue($facet->id()), function ($value) {
+      // Remove 0 (integer) values, that are unchecked checkboxes.
+      // "0" (string) can be a value (for boolean fields).
+      return $value !== 0;
+    });
   }
 
 }