diff --git a/src/Entity/Facet.php b/src/Entity/Facet.php
index 848713d..df5e2eb 100644
--- a/src/Entity/Facet.php
+++ b/src/Entity/Facet.php
@@ -538,6 +538,7 @@ class Facet extends ConfigEntityBase implements FacetInterface {
     // plugin, so we create it on the fly.
     $facet_source = new FacetSource(
       [
+        'uuid' => \Drupal::service('uuid')->generate(),
         'id' => $source_id,
         'name' => $this->facet_source_id,
       ],