diff --git a/apps/files_external/appinfo/database.xml b/apps/files_external/appinfo/database.xml
index 54ee642ead..e39144931a 100644
--- a/apps/files_external/appinfo/database.xml
+++ b/apps/files_external/appinfo/database.xml
@@ -144,7 +144,7 @@
 			<field>
 				<name>value</name>
 				<type>text</type>
-				<notnull>true</notnull>
+				<notnull>false</notnull>
 				<length>4096</length>
 			</field>
 
diff --git a/apps/files_external/lib/Service/DBConfigService.php b/apps/files_external/lib/Service/DBConfigService.php
index a94b73772e..61cca9a022 100644
--- a/apps/files_external/lib/Service/DBConfigService.php
+++ b/apps/files_external/lib/Service/DBConfigService.php
@@ -208,7 +208,7 @@ class DBConfigService {
 				'type' => $builder->createNamedParameter($type, IQueryBuilder::PARAM_INT)
 			]);
 		$query->execute();
-		return (int)$this->connection->lastInsertId('external_mounts');
+		return (int)$this->connection->lastInsertId('*PREFIX*external_mounts');
 	}
 
 	/**