diff --git a/plugins/facetapi/adapter.inc b/plugins/facetapi/adapter.inc
index 67adce5..a50a557 100644
--- a/plugins/facetapi/adapter.inc
+++ b/plugins/facetapi/adapter.inc
@@ -671,7 +671,9 @@ abstract class FacetapiAdapter {
       else {
         foreach ($this->activeItems['facet'][$facet['name']] as $item) {
           $this->urlProcessor->removeParam($item['pos']);
-          $filter = $item['field alias'] . ':' . $item['value'];
+          // As key of the filter array, the raw input is used, so we have to
+          // encode the field alias.
+          $filter = rawurlencode($item['field alias']) . ':' . $item['value'];
           unset($this->activeItems['filter'][$filter]);
         }
         $this->activeItems['facet'][$facet['name']] = array();