diff --git a/Civi/ContactCats/Processor.php b/Civi/ContactCats/Processor.php
index a432fcd..c1912dc 100644
--- a/Civi/ContactCats/Processor.php
+++ b/Civi/ContactCats/Processor.php
@@ -119,7 +119,7 @@ class Processor {
     $changes = CRM_Core_DAO::executeQuery(<<<SQL
       SELECT id, category_definition_id, next_category
       FROM civicrm_contact_category
-      WHERE next_category <> category_definition_id $singleContactClause
+      WHERE (category_definition_id IS NULL OR next_category <> category_definition_id) $singleContactClause
       ORDER BY category_definition_id, next_category
       SQL);
     $lastChange = [0, 0];