diff --git a/modules/market_management/service.php b/modules/market_management/service.php
index c38896f..699b694 100644
--- a/modules/market_management/service.php
+++ b/modules/market_management/service.php
@@ -279,7 +279,7 @@ function market_management_search_occurrences(PDO $pdo, array $input): array
          INNER JOIN market_category c ON c.id = m.category_id
          LEFT JOIN market_occurrence_day d ON d.occurrence_id = o.id
          WHERE ' . ($where === [] ? 'TRUE' : implode(' AND ', $where)) . '
-         GROUP BY o.id, m.name, c.code, c.name
+         GROUP BY o.id, m.name, m.category_id, c.code, c.name
          ORDER BY earliest_date NULLS LAST, o.id ASC
          LIMIT :limit OFFSET :offset'
     );