diff --git a/install/mysql.sql b/install/mysql.sql
index 040857c8..1356532c 100644
--- a/install/mysql.sql
+++ b/install/mysql.sql
@@ -686,7 +686,8 @@ CREATE TABLE IF NOT EXISTS `default_subdomains` (
   `domain_type_parameter` varchar(255) NOT NULL,
   `concerned` enum('BOTH','MAIN','SLAVE') NOT NULL DEFAULT 'MAIN',
   `enabled` boolean not null default true,
-  PRIMARY KEY  (`id`)
+  PRIMARY KEY  (`id`),
+  UNIQUE KEY `unique_row` (`sub`,`domain_type`,`domain_type_parameter`,`concerned`)
 ) COMMENT='Contains the defaults subdomains created on domains creation';
 
 INSERT IGNORE INTO `default_subdomains` (`sub`, `domain_type`, `domain_type_parameter`, `concerned`) VALUES
diff --git a/install/upgrades/1.1.sql b/install/upgrades/1.1.sql
index 7a902992..0ccd43b1 100644
--- a/install/upgrades/1.1.sql
+++ b/install/upgrades/1.1.sql
@@ -208,7 +208,8 @@ CREATE TABLE IF NOT EXISTS `default_subdomains` (
   `domain_type_parameter` varchar(255) NOT NULL,
   `concerned` enum('BOTH','MAIN','SLAVE') NOT NULL DEFAULT 'MAIN',
   `enabled` boolean not null default true,
-  PRIMARY KEY  (`id`)
+  PRIMARY KEY  (`id`),
+  UNIQUE KEY `unique_row` (`sub`,`domain_type`,`domain_type_parameter`,`concerned`)
 ) COMMENT='Contains the defaults subdomains created on domains creation';
 
 INSERT IGNORE INTO `default_subdomains` (`sub`, `domain_type`, `domain_type_parameter`, `concerned`) VALUES