diff --git a/src/DB/Table/AttributeMappingRulesTable.php b/src/DB/Table/AttributeMappingRulesTable.php
index f088f84588..972dd467b8 100644
--- a/src/DB/Table/AttributeMappingRulesTable.php
+++ b/src/DB/Table/AttributeMappingRulesTable.php
@@ -28,7 +28,7 @@ protected function get_install_query(): string {
     `attribute` varchar(255) NOT NULL,
     `source` varchar(100) NOT NULL,
     `category_condition_type` varchar(10) NOT NULL,
-    `categories` text DEFAULT '',
+    `categories` text NOT NULL,
     PRIMARY KEY `id` (`id`)
 ) {$this->get_collation()};
 SQL;